Historic Alleys

The Kamal, or the Rapalagai

Curiosity, adventure, and profits were always the lure for exploration. While travel across land masses was recorded from the oldest times, sailing the seas proved to be less costly and usually faster. However, it was virtually impossible to shelter in place when the weather turned foul, and shipwrecks and losses continued to grow. Nevertheless, human enterprise, inventions, and refinements with aids to assist navigation across vast stretches of sea or ocean allowed sailors to discover lands and conduct trade with faraway shores.  The spice trade became a prime motivation for medieval sailing and proved to be very profitable over time.

In the beginning, coast-hugging sailboats where land was always in sight, were followed by dead reckoning, but this depended very much on wind direction and speed. Over time, after celestial charts were drawn and a sort of compass was invented, cross-ocean sailing ships with differing sail types started to proliferate, aided of course by ocean currents and monsoon winds. Most ships during the early medieval periods were destined from an Arabian or Gulf port - to some port or the other in Western India, in search of spices, primarily pepper, cloves, cinnamon etc.  On the other side of India, ships sailed through the South China Seas touching Indian, Chinese, Ceylonese ports and many S.E. Asian ports.

Dead reckoning involved tracking position based on an initial position on a chart, and then computed further using speed and elapsed time. It is of course conditional to the ship maintaining course, not affected by winds and ocean currents, and considering that this was usually the case, the method was often erroneous, and secondly it was impossible to figure out if you had gone astray, in the open seas, without landmarks. Another method was to use the position of the sun and its shadows to determine position since stars moved east to west. Color of water, and direction taken by birds at flight with food in their beaks (beaks with food, typically fish meant the birds were flying toward shore and vice versa) were other methods used by sailors. Short crossings in the Mediterranean were also based on knowledge about winds and ocean currents.

Some seafarers were adept at watching the types and direction of waves and tides. Similarly, when the color of the water changed from dark green to light green, it meant sandbanks or an approaching shoreline. Schools of fish, sea snakes, etc. also provided clues of approaching land or specific areas in the sea. Lead lines, a long thread with a weighted lead was dropped overboard to measure depths to aid navigation, and devices such as hourglasses graduated incense sticks, etc. helped measure time, especially at night or when the sun was not visible, though relative time measurement (to establish longitude) was still complicated. Speed was measured using chip logs, a graduated (with knots) length of weighted rope dropped overboard, and knots counted over time (hence the nautical term knots for nautical speed/hour).

The arrival and the use of the compass at sea was quite an important event and helped establish direction. It was of particular importance at night or during cloudy nights when stars or the sun were not visible. This was perhaps pioneered by Chinese sailors and later adopted by the Arabs around the 9^th century. Indian seafarers used the floating fish-style compass or Maccha Yantra during their voyages.

Written directions, charts, warnings, wind speeds, pilot books, and so on completed a nautical directory, typically carried by Muallim’s (navigators). In the case of Indian Ocean or Arabian Sea navigation, the monsoon wind was of considerable use for it blew in a fixed direction either way based on the month/season and so one could theoretically ride the wind-keeping course, with much lower losses. This was perhaps one of the main reasons why the West Indian ports became primary transshipment ports for the Arabian traders and could be reached with monsoon winds.

Generally, sailing in the Arabian Sea proceeding East (or West for the return trip) on the latitude of a specific city, with a steady compass bearing gives you a reasonable chance to reach close to the destination, during the monsoons. Arab ships had the lateen sail which allowed them to sail much closer to the wind than European ships of the time, and an experienced sailor will know the distance in the number of days, as well as some sea marks. These ways are memorized as poems, as from al Majid’s Fawa’id where for example, a chapter is devoted to species of sea snakes and how this can help you know the region you are in.

Celestial navigation – Sailing by the North Star

The most important method was using celestial stars to determine latitude, the angular distance of a place north or south of the earth's equator, usually expressed in degrees and minutes. Longitude in comparison, is the location east or west of the prime meridian, presently at Greenwich. The technique of westing or easting requires one to sail towards the destination latitude, turn, and follow a line of constant latitude.

Mapping the sky and documenting star positions have been important and practiced since time immemorial. Even though Constellations changed through seasons, this knowledge had been used by sailors to determine heading directions and by astronomers and astrologers for various other uses. Developments in celestial navigation involving Kamals, astrolabes, sextants, etc. use the technique of triangulation in establishing position. Put simply, these early tools measured the angle or elevation of the sun or a particular star to determine latitude. Needless to mention that these tools became more and more sophisticated over time, to compensate for various errors and variables.

Viral Kanakku - The hand thumb & finger system

The elementary thumb rule involved the use of a closed fist held horizontally. The viral or finger was the key for measurement of the Coromandel, Malabar, and Laccadives seamen, while the term isba was used by the Arab and Omani sailors.  Gujarati and Kutchi seafarers referred to the Anguli. It was usually pegged at ¾” and became the unit for star altitudes, azimuths, and interstellar great circle arc lengths, and was known as the Kai kanakku in Lakshadweep and Malabar, viral kanakku in Tamilnadu and dhru in Gujarat. Multiples and subunits of the finger measure completed the overall system. Even today, some Indian boatmen make use of such vertically held closed fist units of pidi, kol, thambu (or kayiru) to estimate vertical altitudes. Zam was a unit of distance – the average distance covered by a ship is 8 zams in a day. One finger unit is equal to 8 zams; a closed fist is 4 units and an open palm is 12.

The Khashaba, Kamal, or the Loh (Rapalagai or Kau-velli-palagai)

The das tavoletas, tabuas da India in Portuguese writings

The Pole Star or Polaris, also known as the Northern Star, is the most useful star in the sky, not only because can it be used to orient a person's cardinal direction, but also because its angular height equals the latitude of the observing sailor. Of course, using this star is only possible in the Northern Hemisphere, where the Pole Star is visible. As far as the southern seas were concerned, sailors lined up the tool to a point on the southern cross, this was primarily the case for Chola and Coromandel sailors sailing down to the islands in SE Asia.

This wooden tablet or tablets and strings, with knots along the string, formed a simple but effective latitude measurement device, when used together with compensation tables. While Kashba was the earliest name for the device used by Arabs, the etymology for the more popular word Kamal is still not quite clear. The term used by ibn Majid was Qiyas, not Kamal. Researchers have attributed Sanskrit and Arabic origins, and the South Indian names for the device were Rapalagai (night board) and Kau velli Palagai (Laccadives – kau-velli stands for pole star).

Fatimi explains that the popular conception i.e. Kamal meant ‘epitome of perfection’ is fanciful. He believes the word possibly came after the Persian Kaman or Arabic Qaws (meaning- measure one with another) or Qiyas and the Tamil word Kamal.

The measurements were made thus - Sailors would hold a rectangular plate in front of their face so that the top edge lined up with the North Star and the bottom lined up with the horizon. By measuring the distance between the plate and the tip of their nose with a string tied to the center of the plate, they could determine the latitude of the ship. A knotted cord running from the center of the tablet was held taut between the observer's teeth, and all he had to know was the meaning of the knot in his mouth in terms of ports and landmarks. This number represented the latitude of the observer. The length of the string, and therefore the number of knots, varied from observation to observation as the navigator recorded observations at different latitudes, providing a record of the current position relative to previous travel positions.

On an established route, the string would be knotted at lengths appropriate for each port (its total length not exceeding the outstretched arm). At other times, the string would be knotted at regular intervals, corresponding to the angle covered by a finger held horizontally at arm's length. Over time, the Arabs and later the Chinese developed versions with up to 12 tablets. The Kamal gave way to the Tusi staff (later known as the Jacob’s staff) after or around the 16^th century. Refinements included measurements of two or more stars before a fix, while the pole star measurement constituted the basic. Several situations and conditions are catered to in a navigational guide and experienced sailors were adept at remembering and using the rules and adjustments appropriately. The Kamal was ideal at night, and practical for the knots could be counted by touch (in daytime sun measurement, additional tables were required). The observations were usually made from a sitting-down position ( though most pictures show the navigator standing up) presumably to minimize the effects of ship motion. Ibn Majid also gives practical advice on the problems associated with sighting the horizon in a heat haze and in conditions of bioluminescence.

An important advantage of the Kamal was that the rolling deck of the ship had no effect on Kamal readings as the fixed horizon was the main variable. The quadrant and the early astrolabe were not reliable on a moving deck, as Vasco da Gama himself experienced while at sea. To conclude, it was a good tool in the hands of an experienced navigator armed with calibration tables and charts, multiple star sightings, and on a clear night.

Arab navigators augmented their memories by documenting written sailing directions (in books called Rahmani), although the use of poetry (al Majid’s poems – Fawa’id) indicates the continuing oral tradition. The Rahmani texts included environmental cues, and routes, and also included sketches of landmarks to assist in piloting. Kutchi navigator logs were called Pothis.

The Chinese also started to use the Kamal well after the 9th century and used it at sea to estimate Polaris altitudes, and it was known as the ‘suoxing ban’ with 12 ebony boards. The picture shows charts to Calicut and from Hormuz to Calicut, using the locations of stars as depicted, as used during the Cheng Ho (Zheng He) voyages.

Evolutions and refinements

The lowly Kamal evolved (not in chronological order) into sea astrolabes, quadrants, cross staffs, back staffs, and the sextant. Brief descriptions of these developments are provided below – Astrolabes were exquisite instruments with some versions encompassing several functions, a subject by itself.

Sea astrolabes were used to measure the height of the sun or stars in the sky, comprising a brass disc with a scale and ruler, and compensated for deck movement. By holding the disc at eye level using the ring at the top and adjusting the ruler, sailors could determine the altitude of celestial bodies. The cross-staff was closely related to the Kamal, for it was a long staff with a sliding crosspiece. The navigator held the base of the staff up to their eye and slid the crosspiece until the bottom lined up with the horizon and the top with a star or the sun. But as this meant looking into a blinding sun at times, the back staff was invented where the sailors' backs faced the sun.

The Sextant was an 18^th-century development and relatively accurate. Using mirrors and a scale, the sextant provided navigators with precise measurements that allowed them to determine the distance between objects and calculate their latitude while at sea and looking directly at the sun using filters.

And that brings us to the next problem, the need to measure relative time, to get an idea of longitude. Determining longitude relative to the meridian through some fixed location requires that observations be tied to a time scale, so the longitude problem reduces to finding a way to coordinate clocks at distant places. In the old world, before the advent of chronometers, we had many meridians, and Greenwich was not one of them. Greeks had a line passing through Alexandria and Rhodes, while Indians had set Ujjain as the prime meridian. Islamic scholars used Ptolemy’s basis, Indian meridians, and eclipse timings to draw their charts.

Longitude measurements using Lunar eclipses

The problem of longitude determination is well documented. The standard technique was to use lunar eclipses. The time difference of the commencement of the eclipse at different places and recorded in a chart provides the longitude. Kerala scholars and astronomers used lunar eclipses to measure longitude ( latitude (aksha-amsa) and Longitude (rekha-amsa)) by comparing the exact time of the eclipse at different locations, essentially utilizing the fact that the Earth's rotation creates a time difference based on longitude, with the "Surya Siddhanta" text detailing this method, which considered a prime meridian passing through Ujjain as a reference point for calculations; this allowed them to determine the longitudinal position of a place relative to Ujjain based on the observed time of the eclipse. It would not be out of place to assume that this knowledge was available to Indian as well as Arab navigators. That it was in vogue becomes clear from the dialog between Gama and the pilot at Melinde, for the pilot showed him a chart with vertical and horizontal lines.

PN Chopra explains - The celebrated Indian astronomical work Surya Sidhanta brought by the physician Kuttka to the court of the newly founded capital Baghdad was translated into Arabic by Muhammad al-Fazari to As-Sind Hind in the 9^th century. It is interesting to recall in this connection that the astronomical term Qubbat-ul-arin in Arabic (the supposed division of the polar axis from the meridian line) is derived from the name of the Indian city Ujjain which was believed by the Indian astronomers to be the dividing part of the earth.

Hobson-Jobson provides detail - The name of Ujjain long led to a curious imbroglio in the interpretation of the Arabian geographers. Its meridian, as we have just mentioned, was the zero of longitude among the Hindus. The Arab writers borrowing from the Hindus wrote the name apparently Azin, but this by the mere omission of a diacritical point became Arin, and from the Arabs passed to medieval Christian geographers as the name of an imaginary point on the equator, the intersection of the central meridian with that circle. M. Reinaud solved the mystery by pointing out that Arin was simply a corruption of Ujjain. From Ujjain, it became Uzin in Arabic, and by dropping the dot on ' zi ' it changed into Urin and then Arin.

Interestingly, there is no mention of longitudes in Ibn Majid’s Fawa’id. Could it be that Majid did not know or agree with its use, or was it that he didn’t give away all the trade secrets in his poems? The latter is more probable as the meridians are shown in the Gujarati pilots and Sidi Celebi’s charts. Nevertheless, it is also clear that multiple PM standards were in vogue during this period. As this is a complex but interesting topic, and we will discuss Ujjain, longitude 0, and various related matters in a more detailed and specific article related to that subject.

Gama’s Kamal and Cabral’s experience 1497-98

Barros - among the people who came to visit the ships was a Moor of Gujarat, named Malemo Cana, who, both from the satisfaction which he felt at the intercourse with the Portuguese, and to please the King of Melinde who was looking for a pilot for them, accepted to go with them. Vasco da Gama, after talking to him, was very well satisfied with his knowledge, especially after he had shown him a map of all the coast of India, with the bearings laid down after the manner of the Moors, which was with meridians and parallels very small (or close together), without other bearings of the compass; because, as the squares of those meridians and parallels were very small, the coast was laid down by those two bearings of north and south, and east and west, with great certainty, without that multiplication of bearings of the points of the compass usual in our maps, which serves as the root of the others. When Vasco da Gama showed him the great wooden astrolabe which he had brought and others of metal with which he took the sun's altitude, the Moor was not surprised and said that some pilots of the lied Sea used brass instruments of a triangular shape, and quadrants with which they took the sun's altitude, and chiefly that of a star which they most made use of for their navigation. But that he and the Cambay mariners and those of all India made their navigation by certain stars both in the north and in the south, and also by other notable stars which traversed the middle of the heavens from east to west, and they did not take their distance with instruments like those, but with another which he used; which he brought at once to show, which was of three tablets (or plates).

Per Encyclopedia Britannica- The first meridian, separating a leeward from a windward region, passed through Ras Kumhari (Comorin) and was thus nearly identical to the first meridian of the Indian astronomer which passed through the sacred city of Ujjain (Ozere of Ptolemy) or the meridian of Azin of the Arabs. Additional meridians were drawn at intervals of zams, supposed to be equal to three hours' sail. Some notes from the voyage show that navigation was not easy, for it says - On the following Sunday [April 29] we once more saw the North Star, which we had not seen for a long time….

De Hilster, N. explains - When the fleet arrived at the Indian coast, on 18 May 1498, they were near Mount Eli (Ezhimala Hill), which is only 50 nautical miles (50 arcminutes or only half an isba) north of Calicut (Kozhikode). How accurately the Kamal would have allowed him to navigate is unknown, although from modern experiments with inexperienced observers, as discussed below, it seems that observations to within half a degree (30 nautical miles) were possible. An experienced navigator may have known for certain its latitude well within that margin and therefore would have steered to a target location roughly double that uncertainty north of his final destination in order to be sure that he arrived north of it and could then follow the coast ahead of the prevailing winds. So although the kamal was not good enough to determine absolute position for a direct landfall, the pilot seemed to have been aware of his relative position while crossing the Indian Ocean in relation to Calicut well within one isba and apparently well enough to know that they would arrive to the north of it. Vasco da Gama must have been impressed as he took some examples of the Kamal back home.

Vasco da Gama took the Kamal to Portugal, and Portuguese pilots were commissioned to experiment with what they called ' Tavoleta da India ' ( ' little boards of India ' ) during Cabral's voyage in 1500. It was modified to read degrees or inches rather than finger widths.

The GPS – Global positioning system

Today, we are comfortable using the GPS, wherever we are on Earth. GPS satellites transmit signals that are crucial for determining a user’s exact location. These signals, which travel at the speed of light, include detailed information about the satellite’s position and the exact time the signals are sent. This information is encoded into a microwave signal which is then picked up by GPS receivers. The time for the signal transfer from the satellite to the receiver is measured, which is then used to calculate the distance between them.

A final aspect – It was widely believed that Hindus stayed away from the seas and from a Malabar perspective, it was indeed so in the medieval period. While this is right to a point, there were many Hindu sailors and navigators especially from South India and Gujarat sailing to parts on either side of India. It is also clear from the many Gujarati Pothi’s or ship logs published recently, that many a sailor or navigator belonged to the Hindu Koli caste. It is also the case that after voyages became frequent following Dutch and British arrivals, new restrictions and ocean taboos were reapplied by local kingdoms.

And that, my friends, will take you next to my next study – that of a Gujarati Muallim, and his fascinating story dating to the 18^th century.

References

Technology of Indian Sea Navigation (c. 1200–c. 1800) - B. Arunachalam
Indigenous tradition of Indian navigation with special reference to South India – B Arunachalam
Kamal or Rapalagai - CK Raju
The history of the Kamal – S Q Fatimi
Indian Seafaring: The Precept and Reality of Kalivarjya - Lotika Varadarajan
Medieval Arab navigation on the Indian Ocean: Latitude Determinations - Alfred Clark
Indian boat-building traditions. The ethnological evidence - Lotika Varadarajan
Kamal, an instrument of celestial navigation in the Indian Ocean, as described by Ottoman mariners Piri Reis and Seyid Ali reis - Gaye Danışan Polat
The role of the Arab traders in western India during the early medieval period - V. K. Jain
Arab-seafaring-in-the-Indian-ocean-in-ancient-and-early-medieval-times – George F Hourani
Navigation on wood - de Hilster, N.
Arab navigation in the Indian Ocean before the coming of Portuguese -Tibbets, G. R.
Cultural foundations in mathematics: The nature of mathematical proof and the transmission of calculus from India to Europe in the 16th century - Raju, C. K. (2007)