The sailors of the Middle Ages and the era of the Great Geographical Discoveries made great contributions to humanity. At the same time, the methods they used in their voyages to determine the location of the ship, to map the outlines of the coast and determine their length, to put it mildly, left much to be desired. As a memory of some of these techniques, specific terms have been preserved in maritime navigation to this day.
A device for measuring the speed of a ship is still called “lag” - from English word“log” – log, wooden block. These logs were tied to a rope with knots and thrown overboard from the bow of the ship. An hourglass was used to measure the time it took for the log to move to the stern, and then count the number of knots that passed through the hands of the sailor releasing the rope. This is where the nautical term “knot” (in English – “knot”) comes from, a measure of the speed of a ship (one nautical mile per hour or 1.85 km/h).
European sailors of the 15th-16th centuries, like the Arab “Sinbads” of the 9th-12th centuries, did not use the concept of “latitude”, since it could only be determined at the moments of lunar and solar eclipses, which did not occur often. Determinations of longitude on the open sea based on the distance traveled by the ship, which was calculated based on the course of the ship and its speed, were so approximate that many Pacific islands and archipelagos were successfully “discovered” by the Portuguese and Spaniards several times. One of Magellan's helmsmen, for example, made a mistake when determining the longitude of the Philippines by 52° 55" (!).
By the middle of the 18th century, navigators knew the outlines of all the main continents and islands of the Atlantic, Pacific and Indian oceans, with the exception of Antarctica. However, their position was determined very imprecisely, and most maps of that time were almost impossible to use. In this regard, many islands and archipelagos, for example, in the Pacific Ocean, were “lost” for many years after their discovery.
Only in 1750, on the basis of the improved “quadrant,” a new device, the “sextant,” was created, which for the first time made it possible to determine the degree of latitude from on board a ship. Longitude, due to the inability to accurately determine time in sea conditions, was not determined at all. Precise pendulum clocks, invented in 1657 by Christiaan Huygens, were unreliable at sea. In 1707, due to a gross mistake by the flagship navigator when determining longitude, the English fleet ran into the rocks of the Isles of Scilly, resulting in the senseless death of many English sailors. Only after this, in 1714, the English Parliament announced a prize of 20 thousand pounds sterling for the inventor of an accurate marine clock. The criterion for their accuracy was the condition that during the voyage from England to the West Indies and back, the sailing error did not exceed two minutes.
In 1729, the parliamentary commission was offered the first example of such a watch, made by the English master John Harrison and passed tests for accuracy during the voyage to Lisbon. It took the author of the first “chronometer” another thirty years to bring his brainchild to perfection. The fourth sample of Harrison's watches, proposed by him in 1761 to the Bureau of Longitudes under the British government, was less than two minutes behind on the voyage to Jamaica and back, and the lag was only 15 seconds on the voyage to Barbados and back (156 days). After this, almost fifteen more years passed in disputes and courts, during which John Garrison defended his copyrights to the invention. Finally, in 1775, the eighty-two-year-old poor inventor finally received the prize, after which he died a year later. The fates of geniuses, as we see, have not been easy at all times.
Thus, at the turn of the 18th and 19th centuries, marine science finally received a watch that, despite the motion, consistently showed the exact time necessary to measure geographic longitude. After this, the precise “linking” of open lands to the map began, which made it possible to determine the real boundaries and sizes of individual parts of the World Ocean.
Navigation translated from Latin means “navigation, navigation.” This component complex of marine sciences, which emerged from them in the process of development of navigation. This includes navigation - focusing on navigational aids, marine astronomy - which studies methods for determining the coordinates of a ship using celestial bodies; and navigation aids, with the help of which dead reckoning is carried out and the location of the vessel is determined.
The very history of people is inextricably linked with the sea and navigation. Human remains dating back more than 30,000 years have been found in the Americas, and many of these ancient people swam across the ocean. How did they do it? Thor Heyerdahl, during his ocean expeditions on prototypes of ancient ships, proved that this was possible. The first ships are known to us from ancient Egyptian records - these are quite sophisticated ships on which the Egyptians carried out brisk trade along the Nile and by sea. These records are more than 4 thousand years old. Since this ancient time, the need for navigation has already arisen.
What questions did the ancient sailors face? Yes, the same as in our time. This is determining your location and direction of travel. At first, busy sea trade routes ran along the coasts, and navigation was carried out along coastal landmarks. If they had to sail across the ocean, then before the eyes of the ancient travelers there was only one landmark - the stars. The cardinal directions were determined by the movement of the sun. And by observing the stars for a long time at night, you can identify stationary objects among them. These are the North Star in the Northern Hemisphere and the stars in the constellation Southern Cross in the Southern Hemisphere. Most likely, focusing on these stars, ancient people explored new spaces and populated continents and islands. The ancients also noticed that although the stars move, the distances between them do not change. Before people's eyes there was a stunning picture of the moving celestial sphere. Now we know that the Earth moves and we move with it. But these observations marked the beginning of astronomy and celestial navigation.
Ancient Phoenician ship. Image on the sarcophagus
The first navigation maps
In order to successfully navigate in space, people sought to build a model of this space in order to know where they were and where to go. Some peoples used an oral tradition, when information about sea routes was transmitted in the form of stories or chants. Sometimes they also used knotted writing. But even a schematic image, a plan of the area, was more clear. This is how cards began to appear. The Polynesians, who crossed the vast Pacific Ocean, had woven mats with the designation of islands and reefs. The Egyptians painted on reeds. However, these maps, despite their great accuracy in describing specific areas and their features, did not answer the main question - in what exact place is the navigator currently located? How long does it take him to get to the chosen port? There was already a fixed point of reference - these were the stars. I had to come up with and decide how to indicate my location on the map. But the original maps were unfortunately inaccurate, because the round surface of the Earth is difficult to plot on a map plane without distortion. Moreover, according to ancient ideas, the earth was flat, which introduced even greater inaccuracy. However, trade developed, especially strongly in the Mediterranean region. Gradually, enormous knowledge was accumulated in navigation, astronomy and other sciences, which was later collected in ancient Greece. These sciences were developed later, during the Roman Empire. The Greeks, using their observations and information collected from their predecessors, plotted the outlines of known lands on maps. To indicate the location of these lands and other objects, a coordinate grid was applied to the map. The invention of this well-known grid on maps of parallels and meridians also belongs to the ancient Greeks. The concept of latitude and longitude for determining one's location arose again in Greece as a result of constant observations of the position and height of the Sun during the day and the height of stars above the horizon at night. The measurement measure chosen was the change in the position of the Sun. Observing the luminaries, the Chaldeans divided the circle into 360 parts, where one part - a degree - was the movement of the Sun in the sky by the size of its disk. The degree was divided into 60 minutes of arc, since these people had a sexagesimal number system. This knowledge was learned and developed by the Greeks. Gradually, such concepts as horizon, ecliptic, and celestial equator entered science. Without these astronomical concepts, it is impossible to determine exact coordinates.
Modern three-dimensional star map
Already in the third century BC. The Greek scientist Eratosthenes determined not only that the Earth is round, but also very accurately calculated the circumference and radius of the earth's sphere. He used an equidistant cylindrical projection in his maps, which gave greater accuracy on maps showing small areas of the earth's surface. Another Greek scientist, Hipparchus, in the third century BC, covered the entire earth with a grid of meridians and parallels. Now it became clear in which area of the map you need to find your coordinates. A little later, the Roman geographer Marinus of Tire compiled accurate nautical charts. For some areas, it very accurately calculates longitude and latitude and plots them on a grid of parallels and meridians. His information was later used by the famous scientist Ptolemy in his works. Marinus, like Eratosthenes, even tried to portray full model Earth - globe. His calculations and maps were so accurate that they were adopted as a basis by the Portuguese in the 15th century.
The works of a later scientist, Ptolemy, gave a huge impetus to the science of geography and navigation. Ptolemy drew a map of the world in a conical projection, with parallels and meridians; he designated a grid of coordinates, calculated in degrees, where latitudes were measured from the equator, and longitudes from the westernmost point of the then known world. He interviewed a huge number of merchants and sailors and quite accurately described the coasts and countries, even those that he had not seen. He described a huge number of new places and gave their coordinates. In addition to accurate information, he recorded people’s inventions on maps, so in his maps one can find, for example, lands inhabited by the Dog Head people and other miracles. Subsequently, after Ptolemy, nothing new was invented in cartography, and after the collapse of the Roman Empire, completely dark times began.
Ptolemy's map in modern processing. It quite accurately indicates the lands known to the Greeks at that time
Ancient navigational instruments
The very first navigational instrument was the eyes of the ancient navigator. But with the development of navigation, this was no longer enough. To accurately determine the angle of the luminaries above the horizon, special tools were required. This is how the gnomon first appeared, which was a tall pillar; the time and height of the Sun above the horizon were determined by the ratio of the lengths of the pillar and the shadow from it. The gnomon, in the form of a board with a pole on it, was first used by the Greek merchant and navigator Pytheas to determine latitude back in the 4th century BC. The merchant violated the then-existing ban and went beyond the Pillars of Hercules into the open Atlantic Ocean, where he made his observations. Despite the primitive instrument and excitement, the traveler took readings with an accuracy of several arc minutes. Later, a quadrant was used for celestial navigation observations. The quadrant was regular board carved from stone or wood. On its surface were drawn vertical and horizontal lines and a 90° arc connecting them, divided into degrees and their parts. A ruler was placed in the center of the arc and could be moved.
Quadrant
The astrolabe, which was used starting from the second century BC, became a more advanced instrument. until the 18th. The astrolabe was essentially a model of the celestial sphere with its important points, circles, poles and axis mundi, meridian, horizon, celestial equator and ecliptic. It was not easy to make observations with such a device. Observing the Sun, Moon or known stars, the ancient astronavigator brought circles complex instrument V correct position, after which he calculated the longitude and latitude of the observed star using scales graduated on circles. The most famous mechanism that has come down to us is the ancient Greek device of 32 gears “Antikythera”, raised from the bottom of the sea. Based on the surviving inscriptions on it, we can conclude that this is a celestial navigation device. The mechanism could calculate the configurations of the movement of the Sun, Moon, Mars, Jupiter, Saturn, lunar and solar eclipses. The estimated time of manufacture is the period between 100 - 150 BC.
Ancient celestial navigation device
Another device that modern navigators cannot do without - a compass - was also invented in ancient times. The inventors of the compass, the Chinese, according to the entries in their books, began to use the magnetic compass not only for religious needs, but also for navigation about 300 years BC. However, copies of a compass from a later period have reached us. It looked like a magnetized spoon, with its handle pointing south. The Chinese associated each side of the world with its own color. For example, the south was associated with the color red - modern compasses follow this tradition.
Chinese compass
Pilot
Since the voyages of the Egyptians and Phoenicians, huge amounts of information have been accumulated about the coastline, ports of refuge, and anchorages. This knowledge formed the basis of maps and was later used even by Europeans in the Middle Ages. Also, ancient sailors, going out into the ocean, were faced with the phenomenon of ebb and flow. Subsequently, the knowledge was systematized, and already in the ancient Greek navigation, for example, they wrote: “The entire Indian country has a lot of rivers and a very high tide, which intensifies during the new moon and full moon for three days, and is weaker in the intermediate phases.” .
A certain difficulty in historical times was the accurate measurement of time and distance. To measure time they used water or hourglass, and distances were measured by eye. IN Ancient Greece to assist captains, a lighthouse system was also adopted. Very famous Alexandrian lighthouse 120 meters high. Many sculptures placed on the shore also served as coastal landmarks for ships. The famous statue of the Colossus of Rhodes, 36 meters high, was visible for miles. And the entrance to large ports at night was illuminated with light - large fires.
The first seafaring schools
With the development of merchant shipping and the increase in the number of sea voyages, the need arose for the transfer of knowledge. There are no mentions of maritime schools of ancient times; most likely, knowledge was passed on orally and in a close circle. One of the ancient famous schools was the school of navigation in Polynesia. On the island of Raiatea, a place was discovered where the expansion of the Polynesians to the rest of the islands of the Pacific Ocean came from, and a place where knowledge about maritime affairs and navigation was transferred - these were the first nautical schools. Representatives of the AMC Yacht Training Center visited this sacred place on the islands. In 2012 we plan to make a second expedition there.
Tapu Tapu Marae on Raiatea Island. Dating back to the 1st millennium BC. These are the surviving remains of one of the first schools of ocean navigation. Photo by Vladimir Vatrunin.
The first textbooks for sailors were written, probably, along with the invention of writing. One of the astronomical navigation textbooks known to us was compiled by Thales of Miletus back 600 years BC. In Greece, the teaching of astronomy, including astronomy for navigation, was carried out in higher educational institutions of that time. The classical schools of navigation known to us were created much later, in the Middle Ages.
Determination of geographical longitude in ancient times.
Or why are there 24 hours in a day?
But really, why are there 24 hours in a day and not 20 or 30? Well, it could be 25 for ease of counting. There are many arguments and explanations about this. Here's another version.
Let's start with specific questions. Who, with such precision, needed to divide the day into such small and even segments in almost prehistoric times? Was the division of the day into day and night, or a more detailed division of the day into day, evening, night and morning, not enough? There was enough for everyone. In the Russian language there are also the concepts of midnight, after midnight, in the morning, dawn, sunset, noon, which further expanded the division of the time of day into smaller periods of time. A similar division of the day into smaller segments of time of day, albeit of different durations, exists in almost all languages and among all peoples. For example, lovers who agreed to meet, in those days, already knew quite precisely when to come to the meeting and how long they would have to wait for the belated partner to the maximum. The answer is quite simple, the day was divided into 24 hours by those who needed it for professional reasons. And only much later did this professional division of the day become common and familiar to the rest of the population.
So who are these pros who divided the day into 24 hours? These are sailors from ancient times. It was they who came up with the idea of dividing the day into 24 hours, but in order. To determine their location, the sailors needed a reference to some global landmarks in space and time. Everyone knows that planet Earth looks like a ball. This ball rotates around its axis and is still moving around the Sun. The Earth rotates once a day around its axis and completes one revolution around the Sun in a year. To put it very simply, we will assume that the Sun “hangs” strictly above the Equator, and the axis (or poles) of the Earth are at right angles to the Earth-Sun line. Even in ancient times, it was noticed that the north pole (or axis) of the Earth looks towards the North Star in the constellation Ursa Minor, and the south pole is directed towards the constellation Southern Cross. For convenience, the globe was divided into the Northern Hemisphere and the Southern Hemisphere. At night, in the northern hemisphere, you can determine where the North is by the Polar Star, and in the southern hemisphere, you can find the South by the constellation Southern Cross. By facing the North, you can determine where the other cardinal directions will be. The South will be behind you, right shoulder will point to the East, the left shoulder will point to the West. The oldest navigational device was magnetic compass. Using a compass, you can determine the cardinal directions at any time of the day and in any weather.
On land, a traveler, having gone to the West, for example, knows that he must return by moving to the East. At sea, a sailor can sail to the same West from some island, but winds, currents and other factors will take him somewhere unknown, and if the island is not visible, then in which direction should he direct his boat to return to the same island? Here, knowledge of only the cardinal directions is no longer enough. There is only one right direction; all other directions will lead the sailor away from his native island.
Let's return again to the simplified Earth-Sun model. There is a very convenient place on Earth, the Equator. On the Equator, the Sun at noon, located at the Zenith (at the highest point), should shine directly above your head, and if you go from the equator to the north side, the Sun will shine from the South. If you go to the south side, the Sun will shine from the north side. Having left the Equator, it is enough to simply determine which direction to go in order to return to the Equator line. In our model, you can also see that moving from the Equator, for example, to the North Pole, the Sun will gradually shift from Zenith to the South and at the Pole it will shine at the very edge of the horizon. Standing at the pole, you can see the Sun not setting beyond the horizon; moving above the horizon it will shine all day long.
By the way, knowing at what angle to the horizon the Sun was at Zenith above the native island (yesterday, the day before yesterday), you can quite accurately determine whether the ship was carried south or north during the voyage. Accordingly, if the Sun rose higher at noon than above its native island, then the island is somewhere in the South. If the Sun is lower than expected, then the island is somewhere in the North.
Here we need to make an explanation and make an addition. Let's try to see how the length of the shadow from the Sun changes during the day. To do this, on a flat area, we will stick a stick into the ground and mark the end of the shadow from the stick closer to noon. For example, small pegs. It is better to start marking the length of the shadow no later than half past ten. The shortest shadow from the stick will indicate True Noon. After conducting this experiment, you will be convinced that True (or Astronomical) noon in a given area does not coincide at all with noon according to the clock or twelve o'clock in the afternoon Local time. At the same time, you will find out the angle of elevation of the Sun above the horizon in your area at True Noon, only for your area. The angle between the ground and the end of the stick-peg can be measured. This will be the Latitude angle of your area. Now let's draw a circle and mark the Equator on the circle. Next, divide the circle from the Equator to the poles by 90 degrees from the center of the circle. Let's put marks on the circles in increments of 10-15 degrees. Where zero degree will be the Equator, and 90 degrees the North or South Poles. At the same time, mark the latitude angle of your area and see where you are on the model of the globe. The greatest latitude is on the Equator. The remaining latitudes encircle the entire globe in parallel lines, which is why the latitudes are also called parallels. As if cutting the entire ball into slices gradually decreasing in diameter. Knowing your latitude, you can go to the latitude or parallel of the island, but here a new problem will arise: where to sail to the East or West to find the island. To do this, you also need to find out the Longitude of the island.
What is Longitude? Imagine a peeled orange. The slices of this orange from one pole through the Equator to the other pole will be lines of Longitude or Meridians. The entire planet is divided into 360 degrees around the Equator. There is a zero longitude or prime meridian, Greenwich. From the prime meridian, longitude goes both to the West, these will be Western longitudes, and to the East. There will accordingly be Eastern longitudes. The maximum longitude, either in the East or in the West, will be equal to 360:2 = 180 degrees. At 180 degrees of longitude, time begins counting throughout the entire globe. It is at 180 longitude that a new day or a new day begins. But longitudes are counted from the prime meridian. And when they determine the location of some point on the planet they say: So many degrees of South (or North) latitude. This means South or North of the Equator. And so many degrees of Eastern (or Western) longitude. Accordingly, to the East or West of the Greenwich meridian. When designating, they can point to such and such a parallel and such and such a meridian, which is the same thing. But the latitude (parallel) is always indicated first and only then the longitude (meridian) is indicated. For example:
Moscow coordinates Latitude: 55°45;07; north latitude Longitude: 37°36;56; e.d. Altitude: 144 m
Coordinates of my Kazan Latitude: 55°47;19; north latitude
Longitude: 49°07;19; e.d.
Altitude: 61 m
Paris coordinates 48° 51’ 12" (48° 51’ 20) north latitude
2° 20’ 55" (2° 20’ 92) east longitude
Height above sea level 40;60 m
If you divide 360 degrees by 24 hours, this is the time the Earth rotates in one day, you get 15 degrees per hour. Knowing the Longitude at some point on the planet, you can determine whether time is behind or ahead of the Prime Meridian. And vice versa, knowing the difference in time from the time of the Prime Meridian, you can determine the Local Longitude. For example, how is it done today?
We turn on the receiver and use the sound signal to check our watch with Universal Time. The time signals of the local capital are heard on the receiver. In Russia it is Moscow. Moscow time (MSK) differs from Universal Time (Greenwich Mean Time) by plus 2 hours. Then, using Universal Time and Astronomical Noon at a specific place in our location, we determine the time difference and, based on this difference, we determine the longitude of our location. As you remember, Latitude can be determined right on the spot and as a result we get the Coordinates of our location. You can also determine coordinates using navigators. I don’t argue which is faster and easier. But not so accurate. Using a conventional receiver, coordinates are determined with an accuracy of 20 centimeters.
In the Age of Historical Discovery (this is the 15th-19th centuries), there were no radios, navigators, or even radio broadcasting. The ships sailed away for years without any communication with their superiors. To determine the exact time, sailors carried with them a whole bunch of very accurate Chronometer watches. Naturally, even the most accurate clocks can be slightly in a hurry or behind, so they took several chronometers at once in order to calculate a more or less accurate time using the arithmetic mean time, and then it was possible to plot relatively accurate coordinates of open lands on maps and find out their location.
There is a small discrepancy in the above. And that no one had sailed anywhere before this? In the sense that until 24 hours in a day were approved, Universal Time, the Prime or Greenwich Meridian, high-precision clocks and sufficiently reliable seaworthy ships were not invented, they sailed only along the coasts “in view of the visibility of the Earth” and the inhabitants of the islands in the oceans further than “knee-deep” in the water” didn’t leave their island? Then how did these islanders get to their islands and how did the fishermen on their ships find their way back to their islands? Moreover, even before the invention of all the novelties described above, there already existed detailed maps of the planet with continents and islands, even those that were rediscovered much later than the invention of chronometers and Universal Time. It sounds implausible, but it happened. This means that even before that there were some reliable ways of determining coordinates without the fairy tales of today’s scientists “On coastal sailing directions for long-distance voyages.” Need examples? Yes, as much as you like.
Pomors from the Russian North traveled across the White Sea on Kochs to the islands of the Spitsbergen archipelago. And from there the mainland lands are not visible, but this did not stop the Pomors from returning back. On the islands of Oceania, local fishermen on their fragile pirogues could sail for weeks to the desired island and return to their family in the same way. But smart scientists refer as an example of a navigator of distant times to a certain sailor Odysseus, who wandered around the Mediterranean Sea for 25 years until he found his home island. During this time, Odysseus grew old, his wife almost got married, his son grew up... This is how the famous hero hurried home from the war on the neighboring island. What’s interesting is that allies from all over the Mediterranean gathered for that war in an instant; no one was twenty-five years late for the planned battle due to ignorance of the road. Probably Odysseus’s companions and himself lost their memories during the war, which is why they took so long to return.
There is a version that ancient sailors somehow navigated by the stars. The version is beautiful, but no one knows how exactly they were guided. According to my version, ancient sailors navigated by the Moon. It is known that the Moon makes one revolution around the Earth in 28 days. Therefore, in one day the Moon travels 360 degrees: 28 = 12.857 degrees. Now we divide 12.857 degrees by the degree size of the Moon (0.53) and we get 24.258 diameters of the Moon. These are the same 24 hours or periods of time that the Moon passes through the sky in a day. The stars in the sky also move towards the Moon at a speed of 30 degrees per month, but this movement can be taken into account and a landmark for the Moon can be found where this Moon should be tomorrow or in a week or a month. The essence of determining longitude by the Moon is as follows: On a site stationary in space, the Moon will move 24 diameters at the same time the next day. If we move east (or west) by 1000 kilometers in a day, then the Moon will accordingly not reach one diameter (or will go over an extra diameter), which is not difficult to note. Of course similar method Determination of longitude is suitable at any distance from the point of determination in latitude, even on the other side of the planet. The closer to the polar regions, the more accurate the measurements will be. The Pomors of the north had a homemade device called the “Matka solar compass”, and with this device the Pomors could easily determine both latitude and longitude. And also draw up detailed maps of coasts and islands. There are suggestions that Russian Pomors inhabited the Far Eastern coast and the lands of Eastern Siberia even before the birth of Christ. That is, they reached the Pacific Ocean via the Northern Sea Route and knew how to get back by land.
What homemade devices or even, perhaps, the inhabitants of Oceania simply determined latitude and longitude on their fingers, I don’t know, but it’s unlikely that it was very complicated and abstruse. That was the main thing after all!
Any technical problem has many solutions. You just need to find the most profitable or simplest one.
I would be very grateful if my reasoning for determining longitude on the Moon was calculated and brought to practical application by professionals from Astronomy or other specialists familiar with the physics of the movement of astronomical bodies. I promise co-authorship.
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So was the information contained in the portolans reliable? I think it depended on the tasks assigned to them. They were quite suitable for solving “local” applied problems - getting from point A to point B. Navigation in the Mediterranean Sea was quite well studied, since it was constantly supported by large pilotage schools, such as the Genoese, Venetian or Lagos. Portolans were completely unsuitable for understanding the whole world, confusing researchers more than helping them.
It was only from the end of the 13th century that the first attempts at ocean navigation, as well as the wider use of the compass, revealed the need to actually display the coastal topography on a flat sheet of paper, indicating the winds and the main coordinates.
After the 14th century, portolans are often accompanied by rough outline drawings of the Mediterranean coast and the Atlantic coasts of Western Europe. Gradually, ships leaving for ocean voyages begin to get involved in the work of drawing up more accurate portolans and drawings.
Somewhere around the beginning of the 15th century, real navigation maps. They already represent a complete set of information for the pilot: coastal topography, a list of distances, indications of latitude and longitude, landmarks, names of ports and local inhabitants, winds, currents and depths of the sea.
The map, the heir to the mathematical knowledge acquired by the ancients, increasingly accurate information about astronomy and thousands of years of experience in navigation from port to port, becomes one of the main fruits of the scientific thought of the discoverers: from now on, during long voyages it is necessary to compile reports necessary for a complete display of knowledge about the world. Moreover, the first appeared ship's logs! Of course, sea voyages have been described before, but now this is beginning to become a regular occurrence. He was the first to introduce a mandatory ship's log for the captains of his caravels. Captains had to write down information about the shores daily, indicating coordinates - an extremely useful task for drawing up reliable maps.
Despite the desire to clarify and verify that motivated the most famous cartographers (Fra Mauro in 1457 claimed that he was unable to fit into his map all the information that he managed to collect), fantasies, legends, and fiction surrounded any cartographic work with a kind of “folklore” aura : on most maps dating before the 17th century, we see how, in place of little-known or insufficiently explored regions, images of various monsters, drawn from ancient and early Christian mythologies, appear.
Quite often, the compiler, when describing the inhabitants of remote corners, resorted to speculation. Areas explored and brought under the rule of European kings were marked with coats of arms and flags. However, magnificently painted vast compass roses could not be of any use if they were incorrectly oriented or marked in erroneous lines of “diamonds” (a primitive orientation system that predated the system of meridians and parallels). Often the cartographer's work became a real work of art. At the courts of kings, planispheres were looked at like canvases, sailors who had embarked on long journeys could be seen behind them, monsters caused trembling, distances traveled and intriguing names fascinated. It took a long time before the custom of making a decorative map gave way to truly useful cartography, devoid of all fiction.
This explains the distrust with which great navigators, and first of all Christopher Columbus, belonged to the decorated maps of the 15th century. Most sailors preferred to rely on their knowledge of winds, bottom topography, currents and observations of the celestial sphere, or tracking the movement of schools of fish or flocks of birds, in order to navigate the vast expanses of the ocean.
Undoubtedly, it was in the 15th century, thanks to the Portuguese navigators, and then the voyage of Columbus and, finally, the round-the-world voyage of Magellan in 1522, that humanity was able to test in practice the calculations of the ancient Greeks and the idea of the sphericity of the Earth. Many navigators now received concrete knowledge in practice indicating the sphericity of our planet. The curved line of the horizon, the movement of the relative height of the stars, the increase in temperature as one approaches the equator, the change of constellations in the southern hemisphere - all this made obvious a truth that contradicted Christian dogma: the Earth is a sphere! All that remained was to measure the distances that had to be covered on the open sea to get to India, in a southern direction, as the Portuguese did in 1498, or in a western direction, as Columbus seemed to do when he encountered an insurmountable obstacle on his way in 1492. the face of both Americas.
Columbus was well acquainted with the cosmographic literature of that time. His brother was a cartographer in Lisbon, and he himself tried to build a globe based on the available atlases, modern and ancient treatises on cosmography. He, however, made, following his “Imago Mundi” (1410), a gross mistake in assessing the distance between Portugal and Asia, underestimating it (there is a hypothesis that he did this deliberately). However, he heeded the advice of eminent cartographers such as (who believed in a sea route to the west), (the future Pope Pius II) and (later the author of a fairly accurate globe).
Beginning in 1435, Portuguese and Italian sailors made it a rule to sail at a distance from the African coast to avoid dangerous zones and changeable winds. The coastal area, replete with reefs and shoals, indeed presented an obvious danger of shipwreck.
However, such a significant distance from the coast that it is lost from sight presupposes the ability to navigate the open sea on a flat, monotonous space without lighthouses, limited only by the horizon line. And 15th-century sailors lacked the theoretical knowledge of mathematics and geometry necessary to accurately determine their location. As for measuring instruments, things were even worse with them. Until the 16th and 17th centuries, none of them were truly good at it. The maps, although constantly updated, had significant gaps.
To appreciate the extraordinary courage of the sailors who mastered the near and then the far Atlantic, one must remember what pitiful means they had to determine their location on the open sea. The list will be short: the sailors of the 15th century, including Christopher Columbus, had practically nothing that would help them solve the three main tasks of any navigator setting off on a long voyage: to keep a course, to measure the distance traveled, to know with accuracy their current location.
The 15th century sailor had at his disposal only a primitive compass (in various variations), a crude hourglass, error-infested maps, approximate tables of the declination of the stars and, in most cases, erroneous ideas about the size and shape of the Earth! In those days, any expedition across the oceans became a dangerous adventure, often with fatal consequences.
In 1569 Mercator made the first map in conformal cylindrical projection, and the Dutchman Luka Wagener put into use atlas. This was a major step in the science of navigation and cartography, because even today, in the twenty-first century, modern nautical maps are compiled into atlases and made in Mercator projection!
In 1530, a Dutch astronomer Gemma Frisius(1508-1555) in his work “Principles of Astronomical Cosmography” proposed a method for determining longitude using a chronometer, but the lack of sufficiently accurate and compact watches left this method purely theoretical for a long time. This method was called chronometric. Why did the method remain theoretical, since watches appeared much earlier?
The fact is that clocks in those days could rarely run without stopping for 24 hours, and their accuracy did not exceed 12-15 minutes per day. And the watch mechanisms of that time were not adapted to work in conditions of sea motion, high humidity and sudden temperature changes. Of course, in addition to mechanical ones, maritime practice Hourglasses and sundials were used for a long time, but the accuracy sundial, “factory” time hourglass were completely insufficient to implement the chronometric method of determining longitude.
Today it is believed that the first precise clocks were assembled in 1735 by an Englishman John Harrison(1693-1776). Their accuracy was 4-6 seconds per day! At that time, this was simply fantastic accuracy! And what’s more, the watch was adapted for sea travel!
Ancestors naively believed that the Earth rotates evenly, lunar tables had inaccuracies, quadrants and astrolabes introduced their own errors, so the final errors in coordinate calculations amounted to up to 2.5 degrees, which is about 150 nautical miles, i.e. almost 250 km!
In 1731, an English optician improved the astrolabe. The new device, called octant, made it possible to solve the problem of measuring latitude on a moving ship, since now two mirrors made it possible to simultaneously see both the horizon line and the sun. But the octant did not get the glory of the astrolabe: a year earlier Hadley had designed sextant- a device that made it possible to measure the location of a ship with very high accuracy.
Basic device sextant, i.e. a device using the principle of double reflection of an object in mirrors, was developed Newton, but was forgotten and only in 1730 was Hadley reinvented independently of Newton.
The marine sextant consists of two mirrors: an index mirror and a fixed translucent horizon mirror. Light from a luminary (star or planet) falls on a movable mirror and is reflected on the horizon mirror, on which both the luminary and the horizon are simultaneously visible. The angle of inclination of the index mirror is the height of the luminary.
Since this site is about history, and not about navigation, I will not go into the details and features of various navigational instruments, but I want to say a few words about two more instruments. These are lot() and lag().
In conclusion, I would like to briefly dwell on some historical dates in the history of the development of navigation in Russia.
The year one thousand seven hundred and one is perhaps the most significant date in domestic navigation, since this year the emperor Peter I issued a decree on the establishment of “Mathematical and Navigational, that is, nautical and cunning sciences of teaching.” The year of birth of the first domestic navigation school.
Two years later, in 1703, the teacher of this school compiled the textbook “Arithmetic”. The third part of the book is entitled “Generally about earthly dimensions, and what also belongs to navigation.”
In 1715, the senior school was transformed into the Naval Academy.
1725 is the year of birth of the St. Petersburg Academy of Sciences, where such luminaries of science taught as, Mikhail Lomonosov(1711-1765). For example, it was Euler’s astronomical observations and mathematical description of the motion of the planets that formed the basis for highly accurate lunar tables for determining longitude. Bernoulli's hydrodynamic studies made it possible to create perfect logs for accurately measuring the speed of a ship. Lomonosov's work concerned the creation of a number of new navigation instruments, which served as prototypes for instruments that are still used today: course plotters, recorders, logs, inclinometers, barometers, binoculars...
The history of navigation, and therefore piracy, is closely connected with the history of navigation and cartography. The history of navigation, and therefore piracy, is closely connected with the history of navigation and cartography. When were nautical maps invented? How did people in ancient times navigate the sea? Answering these questions is not as simple as it might seem at first.
Of course, sailing along the coast does not require maps or any special ways orientation. It is enough to study the coastline. Most ancient sailors did just that; by the way, this greatly simplified the equipment of the ship: it was not necessary to have a significant supply of provisions and fresh water. And if so, then it would seem that devices for navigation should have appeared quite recently. But the thing is that long voyages took place thousands of years ago, while the first information about any navigational instruments dates back to a rather late time.
Modern science believes that the Indians of both American continents, as well as the Papuans of the islands of Oceania, descend from Siberian tribes that migrated across the ocean. Siberians left their “mark” in the places where the Mayans, Incas, Aztecs and other tribes lived. However, there are other hypotheses in this regard. For example, scientists do not exclude the migration of the Phoenicians or other peoples who inhabited the Mediterranean across the Atlantic Ocean. The famous traveler and scientist Thor Heyerdahl undertook several successful expeditions to the Kon-Tiki and Ra in order to confirm this assumption.
Be that as it may, we are certainly talking about sailing across the ocean, far from the shores, where the only reference point could be the starry sky, the sun and the moon. Today it is believed that the first navigators used entrete orientation (that is, by eye) using the celestial bodies. East and west were determined by sunrise and sunset, and north and south by the position of the North Star or stars from the Southern Cross constellation.
Ancient sailors often took bird cages with them.. If a ship was lost at sea, the sailors would periodically release a bird (often a black raven). If the bird returned back, then there was no land nearby, and if it flew away in a certain direction, then the ship followed it, completely trusting the bird: that means the bird was flying to land. This technique was especially popular among the Scandinavians.
Ptolemy's map (2nd century AD) Thanks to a survey of merchants and sailors, as well as reading all the reports of ancient travelers, he managed to draw a map of the world in a conical projection, with parallels and meridians
This probably gave impetus to the appearance of portolans, although I would not dare to name the exact time of the birth of these cards, even approximately. What are portolans?
Mediterranean sailors felt the need to have accurate guides that would help them conduct trade over very long distances from their home ports. Due to the fickleness of the winds, it was not always possible to move away from the shores of the Mediterranean Sea, since the capricious weather of the Mediterranean made these trips very dangerous. Even in the Middle Ages, most movement in the region still took place within sight of the coast.
During the times of the Cretan, Phoenician and Egyptian navigators, many ships plied the Mediterranean, but due to the need to stay on shore, only one trip from east to west could be made per year. From October to March, trade practically ceased, and some routes from north to south (Greece - Egypt, Gaul - North Africa), with a headwind, took entire months.
Thus, in ancient times and the early Middle Ages, the first maps became guides for moving from port to port rather than accurate descriptions of the coast. The pilots were more interested in an accurate knowledge of the topography of the coast, the presence of shoals, the constancy of winds, and the location of port cities, rather than in a scientific understanding of the surface of the Earth. Without a compass to steer the ship, without any means of determining latitude (especially when clouds covered the sky), the only option left for the pilot - be he Egyptian, Greek, Venetian or Catalan - was to draw a map! He needed a portolan (from the Italian “portolano”, that is, “a guide to ports”). In other words, a guidebook was required that would combine information about coasts, ports, winds, depths and currents collected by navigation professionals since antiquity, information with the help of which trade was carried out in Mediterranean ports in the Middle Ages.
The first information about the direct nautical maps of Marin of Tyre dates back to the 2nd century BC. e., although maps generally existed already among the ancient Polynesians in the 5th century BC. e. and were mats woven from plants depicting islands and reefs.
Maps of that period differed little from very schematic plans, and the larger the territories depicted, the less accurate the maps were: after all, the Earth is round, and large areas of its surface cannot be shown on a plane without distortion!
One of the solutions to this problem was found two thousand years ago by Eratosthenes (276–196 BC), who began to use a square equidistant cylindrical projection when creating maps. By the way, it was Erastophenes, observing the midday height of the sun in Alexandria and Aswan, who determined the radius of the Earth (6366.7 km) with such high accuracy that people are still amazed at this! And the camel “acted” as a measuring instrument! Erastofen determined the distance between two points by calculating the average number of steps, and, knowing the difference in the length of the sun's shadow, carried out simple calculations. Now this is an elementary geometry problem about the similarity of two triangles, but in those days it was a miracle.
To read a map better, you need a navigational guide. Pilotage (from the Dutch loodsen - to lead a ship) - a guide for sailing in a particular water basin with a detailed description of its navigational features. The oldest surviving sailing guide is that of the Greek Skilakas (VI century BC), which described in detail the distances between ports, their equipment, anchorages, navigational hazards...
In general, long before medieval cosmographers, people made attempts to depict the Earth in the shape of a globe. The already mentioned Eratosthenes and Marinus of Tire were like this, and so was Ptolemy: they boldly drew maps based on their own calculations. When Palla Strozzi brought a complete copy of Ptolemy’s “Geography” to Constantinople, its translation into Latin became, as they would say today, one of the “bestsellers” of the nascent printing industry! Ptolemy was a Greek scholar from Alexandria who lived from approximately 90 to 160 AD. Thanks to a survey of merchants and sailors, as well as reading all the reports of ancient travelers, he managed to draw a map of the world in a conical projection, with parallels and meridians, that is, a grid of coordinates calculated in degrees, where latitudes were measured from the equator, and longitudes from the westernmost point the then known world. Partially erroneous, very inaccurate in many of its places, “Geography” nevertheless represented a tangible stage in the mathematical understanding of the world.
The quadrant is a primitive instrument for measuring the altitude of stars and determining latitude.
As has already become clear, the concepts of geographic latitude and longitude for unambiguously determining a location on the Earth’s surface first arose in Ancient Greece. During the day (at noon) latitude was determined by the length of the sun's shadow, at night - by the height of certain stars above the horizon. Today, the palm in the use of latitude and longitude is awarded to Hipparchus of Nicaea (c. 190–125 BC), who proposed a method for determining the longitude of different points by measuring local time during observation lunar eclipse. In addition, Hipparchus invented the astrolabe (Greek astron - “star”, and labe - “grasping”) - a goniometric instrument that served from ancient times until the beginning of the 18th century to determine the position of celestial bodies. Previously, a quadrant was used for the same purposes.
In 1342, the mathematician Levi Ben Gershon first described a device later called the “Levi stick”. Also called a “crossbow,” it was a simple but ingenious device that could be used to measure the relative height of the sun at its zenith in relation to the horizon. Thanks to the tables of Zacuto and Visigno (1465), used simultaneously, it was possible to determine one's location to within one or two degrees of latitude.
Levi's wand is a medieval tool for determining the latitude of a location.
Evolution European cartography up to the 16th century, it reflects a gigantic collective effort in order to get an idea of the world, drawing information from the crude empiricism of the portolans. Thus, sailors little by little gain the opportunity to enjoy all the fruits of scientific knowledge of the Earth. In place of descriptions, even quite accurate, but always incomplete, are maps that can give a geometrically correct idea of our planet. But for this it was necessary to get rid of the prejudices of the mythologized consciousness, and at the same time acquire some navigational and topographical tools.
One of the first navigational “instruments” can be considered solarstein (translated from Old Norse - “sun stone”). With its help it was possible to determine the position of the sun in foggy weather. It is mentioned several times in ancient Viking texts. It is assumed that we are talking about a crystal of Icelandic feldspar (cordierite), which had magnetic properties.
The phenomenon of magnetism was noticed by people in ancient times. The history of magnetism is rich in observations and facts, different views and ideas.
Today it is believed that the properties of magnetic iron ore were first described by Thales of Miletus in the 6th century BC. e. These were purely theoretical calculations, not confirmed by experiments. Thales gave an incomprehensible explanation for the properties of the magnet, attributing to it “animation.” A century after him, Empedocles explained the attraction of iron by a magnet by certain “outflows” of some immaterial substance from it. Later, a similar explanation in a more definite form was presented in the book of Lucretius “On the Nature of Things.” There were also statements about magnetic phenomena in the works of Plato, where he described them in poetic form. Scientists of a later time - Descartes, Huygens and Euler - had ideas about the essence of magnetic actions, and these ideas in some respects were not too different from the ideas of ancient philosophers.
Magnetic phenomena have been used in maritime navigation since the early Middle Ages. At the end of the 12th century, in the works of the Englishman Nekam and the Frenchman Guio de Provence, the simplest compass (French boussole) was first described - a device that allows you to determine the magnetic azimuth in the sea. Although in China the compass was used for navigation even before our era. In Europe, it became widespread only in the 13th century.
The first experimenter to study magnets was Peter Peregrin from Maricourt (13th century). He experimentally established the existence of magnetic poles, the attraction of unlike poles and the repulsion of like poles. While cutting the magnet, he discovered that it was impossible to isolate one pole from the other. He carved a spheroid from magnetic iron ore and tried to experimentally show the analogy in the magnetic relationship between this spheroid and the earth. This experience was later (in 1600) reproduced even more clearly by Gilbert.
The first compasses, invented independently of each other in Asia and Scandinavia around the 11th century, came to the Mediterranean coast of Europe in the 12th century and were a board floating in a shell filled with water. Attached to one of its ends was a piece of calamite, a stone with natural magnetic properties, imported from Magnesia in Greece, where it is very common. Such a compass worked well only with slight rocking on the ship.
A). One of the first compasses, which was a board floating in a shell filled with water. A piece of lodestone was attached to one of its ends;
b). The common compass, consisting of a steel magnetic needle rotating on a point located in the center of a small round or quadrangular box ("bossola" in Italian), was most common on board early caravels.
V). A compass or dry compass with an arrow, improved in the Sagra school, was made from a cardboard disk on which a compass rose was drawn. A small magnetized steel strip was fixed under the northern point of the compass rose. This is a more accurate tool to keep you on the right course.
So was the information contained in the portolans reliable? I think it depended on the tasks assigned to them. They were quite suitable for solving “local” applied problems - getting from point A to point B. Navigation in the Mediterranean Sea was quite well studied, since it was constantly supported by large pilotage schools, such as the Genoese, Venetian or Lagos. Portolans were completely unsuitable for understanding the whole world, confusing researchers more than helping them.
It was only from the end of the 13th century that the first attempts at ocean navigation, as well as the wider use of the compass, revealed the need to actually display the coastal topography on a flat sheet of paper, indicating the winds and the main coordinates.
After the 14th century, portolans are often accompanied by rough outline drawings of the Mediterranean coast and the Atlantic coasts of Western Europe. Gradually, ships leaving for ocean voyages begin to get involved in the work of drawing up more accurate portolans and drawings.
Somewhere around the beginning of the 15th century, real navigation maps appeared. They already represent a complete set of information for the pilot: coastal topography, a list of distances, indications of latitude and longitude, landmarks, names of ports and local inhabitants, winds, currents and sea depths are indicated.
The map, the heir to the mathematical knowledge acquired by the ancients, increasingly accurate information about astronomy and thousands of years of experience in navigation from port to port, becomes one of the main fruits of the scientific thought of the discoverers: from now on, during long voyages it is necessary to compile reports necessary for a complete display of knowledge about the world. And what’s more, the first ship’s logs appeared! Of course, sea voyages have been described before, but now this is beginning to become a regular occurrence. Infante Henry was the first to introduce a mandatory ship's log for the captains of his caravels. Captains had to write down information about the shores daily, indicating coordinates - an extremely useful task for drawing up reliable maps.
Despite the desire to clarify and verify that motivated the most famous cartographers (Fra Mauro in 1457 claimed that he was unable to fit into his map all the information that he managed to collect), fantasies, legends, and fiction surrounded any cartographic work with a kind of “folklore” aura : on most maps dating before the 17th century, we see how, in place of little-known or insufficiently explored regions, images of various monsters, drawn from ancient and early Christian mythologies, appear.
Quite often, the compiler, when describing the inhabitants of remote corners, resorted to speculation. Areas explored and brought under the rule of European kings were marked with coats of arms and flags. However, magnificently painted vast compass roses could not be of any use if they were incorrectly oriented or marked in erroneous lines of “diamonds” (a primitive orientation system that predated the system of meridians and parallels). Often the cartographer's work became a real work of art. At the courts of kings, planispheres were looked at like canvases, sailors who had embarked on long journeys could be seen behind them, monsters caused trembling, distances traveled and intriguing names fascinated. It took a long time before the custom of making a decorative map gave way to truly useful cartography, devoid of all fiction.
This explains the distrust with which the great navigators, and first of all Christopher Columbus, treated the painted maps of the 15th century. Most sailors preferred to rely on their knowledge of winds, bottom topography, currents and observations of the celestial sphere, or tracking the movement of schools of fish or flocks of birds, in order to navigate the vast expanses of the ocean.
Undoubtedly, it was in the 15th century, thanks to the Portuguese navigators, and then the voyage of Columbus and, finally, the round-the-world voyage of Magellan in 1522, that humanity was able to test in practice the calculations of the ancient Greeks and the idea of the sphericity of the Earth. Many navigators now received concrete knowledge in practice indicating the sphericity of our planet. The curved line of the horizon, the movement of the relative height of the stars, the increase in temperature as one approaches the equator, the change of constellations in the southern hemisphere - all this made obvious a truth that contradicted Christian dogma: the Earth is a sphere! All that remained was to measure the distances that had to be covered on the open sea to get to India, in a southern direction, as the Portuguese did in 1498, or in a western direction, as Columbus seemed to do when he encountered an insurmountable obstacle on his way in 1492. the face of both Americas.
Columbus was well acquainted with the cosmographic literature of that time. His brother was a cartographer in Lisbon, and he himself tried to build a globe based on the available atlases, modern and ancient treatises on cosmography. He, however, made, following Pierre Ailly and his “Imago Mundi” (1410), a gross mistake in assessing the distance between Portugal and Asia, underestimating it (there is a hypothesis that he did this deliberately). However, he heeded the advice of eminent cartographers such as Toscanelli (who believed in a sea route to the west), Piccolomini (the future Pope Pius II) and Martin Behaim (later the author of a fairly accurate globe).
Beginning in 1435, Portuguese and Italian sailors made it a rule to sail at a distance from the African coast to avoid dangerous zones and changeable winds. The coastal area, replete with reefs and shoals, indeed presented an obvious danger of shipwreck.
However, such a significant distance from the coast that it is lost from sight presupposes the ability to navigate the open sea on a flat, monotonous space without lighthouses, limited only by the horizon line. And 15th-century sailors lacked the theoretical knowledge of mathematics and geometry necessary to accurately determine their location. As for measuring instruments, things were even worse with them. Until the 16th and 17th centuries, none of them were truly good at it. The maps, although constantly updated, had significant gaps.
To appreciate the extraordinary courage of the sailors who mastered the near and then the far Atlantic, one must remember what pitiful means they had to determine their location on the open sea. The list will be short: the sailors of the 15th century, including Christopher Columbus, had practically nothing that would help them solve the three main tasks of any navigator setting off on a long voyage: to keep a course, to measure the distance traveled, to know with accuracy their current location.
The 15th century sailor had at his disposal only a primitive compass (in various variations), a crude hourglass, error-infested maps, approximate tables of the declination of the stars and, in most cases, erroneous ideas about the size and shape of the Earth! In those days, any expedition across the oceans became a dangerous adventure, often with fatal consequences.
In 1569, Mercator compiled the first map in a conformal cylindrical projection, and the Dutchman Luca Wagener introduced the atlas. This was a major step in the science of navigation and cartography, because even today, in the twenty-first century, modern nautical maps are compiled into atlases and made in Mercator projection!
In 1530, the Dutch astronomer Gemma Frisius (1508-1555), in his work “Principles of Astronomical Cosmography,” proposed a method for determining longitude using a chronometer, but the lack of sufficiently accurate and compact clocks left this method purely theoretical for a long time. This method was called chronometric. Why did the method remain theoretical, since watches appeared much earlier?
The fact is that clocks in those days could rarely run continuously for 24 hours, and their accuracy did not exceed 12–15 minutes per day. And the watch mechanisms of that time were not adapted to work in conditions of sea motion, high humidity and sudden temperature changes. Of course, in addition to mechanical ones, hourglasses and sundials were used in maritime practice for a long time, but the accuracy of the sundial and the time to “wind” the hourglass were completely insufficient to implement the chronometric method of determining longitude.
Today it is believed that the first accurate clocks were assembled in 1735 by the Englishman John Harrison (1693-1776). Their accuracy was 4–6 seconds per day! At that time, this was simply fantastic accuracy! And what’s more, the watch was adapted for sea travel!
Ancestors naively believed that the Earth rotates evenly, lunar tables had inaccuracies, quadrants and astrolabes introduced their own errors, so the final errors in coordinate calculations amounted to up to 2.5 degrees, which is about 150 nautical miles, i.e. almost 250 km!
In 1731, the English optician John Hadley improved the astrolabe. The new device, called the octant, made it possible to solve the problem of measuring latitude on a moving ship, since now two mirrors made it possible to simultaneously see both the horizon and the sun. But the octant did not get the glory of the astrolabe: a year earlier, Hadley had designed a sextant, a device that made it possible to measure the location of a ship with very high accuracy.
The fundamental design of a sextant, i.e. a device using the principle of double reflection of an object in mirrors, was developed by Newton, but was forgotten and only in 1730 was it reinvented by Hadley independently of Newton.
The marine sextant consists of two mirrors: an index mirror and a fixed translucent horizon mirror. Light from a luminary (star or planet) falls on a movable mirror and is reflected on the horizon mirror, on which both the luminary and the horizon are simultaneously visible. The angle of inclination of the index mirror is the height of the luminary.
Since this site is about history, and not about navigation, I will not go into the details and features of various navigational instruments, but I want to say a few words about two more instruments. These are lot (lotlin) and lag (laglin).
In conclusion, I would like to briefly dwell on some historical dates in the history of development navigation in Russia.
The year one thousand seven hundred and one is perhaps the most significant date in domestic navigation, since this year Emperor Peter I issued a decree on the establishment of “Mathematical and Navigational, that is, nautical and cunning sciences of teaching.” The year of birth of the first domestic navigation school.
Two years later, in 1703, Magnitsky, a teacher at this school, compiled the textbook “Arithmetic”. The third part of the book is entitled “Generally about earthly dimensions, and what also belongs to navigation.”
In 1715, the senior school was transformed into the Naval Academy.
1725 is the year of birth of the St. Petersburg Academy of Sciences, where such luminaries of science as Leonhard Euler, Daniil Bernoulli, Mikhail Lomonosov (1711-1765) taught. For example, it was Euler’s astronomical observations and mathematical description of the motion of the planets that formed the basis for highly accurate lunar tables for determining longitude. Bernoulli's hydrodynamic studies made it possible to create perfect logs for accurately measuring the speed of a ship. Lomonosov's work concerned the creation of a number of new navigation instruments, prototypes of which are still in use today: course plotters, recorders, logs, inclinometers, barometers, binoculars...
