Kamal
Encyclopedia
A kamal is a celestial navigation
device that determines latitude
. The invention of the kamal allowed for the earliest known latitude sailing, and was thus the earliest step towards the use of quantitative
methods in navigation
. It originated with Arab navigators of the late 9th century, and was employed in the Indian Ocean from the 10th century. It was adopted by Indian navigators
soon after, and then adopted by Chinese navigators
some time before the 16th century.
because its angle to the horizon does not change with longitude or time. The angle can then be measured by counting the number of knots from the teeth to the card, or a particular knot can be tied into the string if travelling to a known latitude.
The knots were typically tied to measure angles of one finger-width. When held at arm's length, the width of a finger measures an angle that remains fairly similar from person to person. This was widely used (and still is today) for rough angle measurements, an angle known as issabah in Arabic
, or a chih in Chinese. By modern measure, this is about 1 degree, 36 minutes, and 25 seconds, or just over 1.5 degrees.
Due to the limited width of the card, the kamal was only really useful for measuring Polaris in equatorial latitudes, which perhaps explains why it was not common in Europe. For these higher-latitude needs somewhat more complex devices based on the same principle were used, notably the cross-staff and backstaff
.
The kamal is still a tool recommended for use in sea kayak
ing. In such an application, it can be used for estimating distances to land.
Around this time (of the Discoveries) the Arabs were using a very ingenious instrument in the Mediterranean Sea that allowed them to know latitude. It was called al-kamal – the guiding line. It was simply a small wooden board with a notch made on top and in the middle of it and a piece of string that was attached to the centre of the board; it could only be operated at night. To find where they were, an operator would adjust the distance of the piece of wood closer or farther away from his eyes in order to have the bottom of the plank levelled with the horizon and the North Star placed inside the notch. The operator would then tie a knot in the string on the point where it touched his nose, and a celestial location was then marked. There were no angles to measure and record or complicated mathematical formulas to consider. From then on the navigator knew that every time the horizon was levelled with the bottom of the board, the North Star was inside the notch, and the distance measured in the string was the same as marked, he was in a place that had the same latitude as the one where he had made those measurements. Portugal had to wait for Vasco da Gama to bring it from India on the first voyage he made there in 1498.
Celestial navigation
Celestial navigation, also known as astronavigation, is a position fixing technique that has evolved over several thousand years to help sailors cross oceans without having to rely on estimated calculations, or dead reckoning, to know their position...
device that determines latitude
Latitude
In geography, the latitude of a location on the Earth is the angular distance of that location south or north of the Equator. The latitude is an angle, and is usually measured in degrees . The equator has a latitude of 0°, the North pole has a latitude of 90° north , and the South pole has a...
. The invention of the kamal allowed for the earliest known latitude sailing, and was thus the earliest step towards the use of quantitative
Numerical data
Numerical data is data measured or identified on a numerical scale. Numerical data can be analyzed using statistical methods, and results can be displayed using tables, charts, histograms and graphs. For example, a researcher will ask a questions to a participant that include words how often, how...
methods in navigation
Navigation
Navigation is the process of monitoring and controlling the movement of a craft or vehicle from one place to another. It is also the term of art used for the specialized knowledge used by navigators to perform navigation tasks...
. It originated with Arab navigators of the late 9th century, and was employed in the Indian Ocean from the 10th century. It was adopted by Indian navigators
Indian maritime history
Indian maritime history begins during the 3rd millennium BCE when inhabitants of the Indus Valley initiated maritime trading contact with Mesopotamia. The Roman historian Strabo mentions an increase in Roman trade with India following the Roman annexation of Egypt. By the time of Augustus up to 120...
soon after, and then adopted by Chinese navigators
Naval history of China
The naval history of China dates back thousands of years, with archives existing since the late Spring and Autumn Period about the ancient navy of China and the various ship types used in war. China was leading maritime power in the years 1405-1433, when Chinese shipbuilders began to build massive...
some time before the 16th century.
Description
The kamal consists of a rectangular wooden card about 2 by, to which a string with several equally spaced knots is attached through a hole in the middle of the card. The kamal is used by placing one end of the string in the teeth while the other end is held away from the body roughly parallel to the ground. The card is then moved along the string, positioned so the lower edge is even with the horizon, and the upper edge is occluding a target star, typically PolarisPolaris
Polaris |Alpha]] Ursae Minoris, commonly North Star or Pole Star, also Lodestar) is the brightest star in the constellation Ursa Minor. It is very close to the north celestial pole, making it the current northern pole star....
because its angle to the horizon does not change with longitude or time. The angle can then be measured by counting the number of knots from the teeth to the card, or a particular knot can be tied into the string if travelling to a known latitude.
The knots were typically tied to measure angles of one finger-width. When held at arm's length, the width of a finger measures an angle that remains fairly similar from person to person. This was widely used (and still is today) for rough angle measurements, an angle known as issabah in Arabic
Arabic language
Arabic is a name applied to the descendants of the Classical Arabic language of the 6th century AD, used most prominently in the Quran, the Islamic Holy Book...
, or a chih in Chinese. By modern measure, this is about 1 degree, 36 minutes, and 25 seconds, or just over 1.5 degrees.
Due to the limited width of the card, the kamal was only really useful for measuring Polaris in equatorial latitudes, which perhaps explains why it was not common in Europe. For these higher-latitude needs somewhat more complex devices based on the same principle were used, notably the cross-staff and backstaff
Backstaff
The backstaff or back-quadrant is a navigational instrument that was used to measure the altitude of a celestial body, in particular the sun or moon...
.
The kamal is still a tool recommended for use in sea kayak
Sea kayak
A sea kayak or touring kayak is a kayak developed for the sport of paddling on open waters of lakes, bays, and the ocean. Sea kayaks are seaworthy small boats with a covered deck and the ability to incorporate a spraydeck...
ing. In such an application, it can be used for estimating distances to land.
Around this time (of the Discoveries) the Arabs were using a very ingenious instrument in the Mediterranean Sea that allowed them to know latitude. It was called al-kamal – the guiding line. It was simply a small wooden board with a notch made on top and in the middle of it and a piece of string that was attached to the centre of the board; it could only be operated at night. To find where they were, an operator would adjust the distance of the piece of wood closer or farther away from his eyes in order to have the bottom of the plank levelled with the horizon and the North Star placed inside the notch. The operator would then tie a knot in the string on the point where it touched his nose, and a celestial location was then marked. There were no angles to measure and record or complicated mathematical formulas to consider. From then on the navigator knew that every time the horizon was levelled with the bottom of the board, the North Star was inside the notch, and the distance measured in the string was the same as marked, he was in a place that had the same latitude as the one where he had made those measurements. Portugal had to wait for Vasco da Gama to bring it from India on the first voyage he made there in 1498.