Kamal

The Kamal was used by Arab sailors since ancient times. This very simple instrument shares the same principle as the cross-staff, and in fact may have been the immediate insiration for the development of the navigational cross-staff. In the Kamal the cross piece is replaced by a card, and the staff by a piece of cord. Of course a cord does not lend itself to fine graduations, and its design reflects the particular use of this instrument and the circumstance of Arab navigators. The Kamal was not generally used to find one's location at sea. Rather it was used to maintain a particular latitude. That is, it was used to keep on course by making sure a particular reference star remained at a specific altitude above the Southern horizon at its meridian. Thus a Kamal might have a series of knots on the cord corresponding to the latitudes of specific destinations. In fact the destinations might be written on the face of the Kamal for easy reference. The Kamal was particularly well adapted to the common situation of Arab sailors on the Indian ocean. For long journeys most sailing would follow the monsoon winds, which blow steadily in either an Easterly or Westerly direction for long periods. Thus one sails before the wind with no tacking required. To find the next port it is only necessary to keep at its latitude and you'll run into it! The Kamal can also be used for layout. A friend uses one to measure off the distance for placing archery targets. He has made a cord such that a six foot friend just walks away until he matches the Kamal and the measurement is done. And the Kamal is easily transported - just wrap the cord around the plate and stick it in a pocket.

Making a Kamal

This Kamal was one of the projects for my 1998 workshop, "Medieval Scientific and Philosophical Instruments." Materials (provided at the workshop - illustration below):

• Wooden rectangle, 3/8" x 6" x 3", with hole drilled in center (about 3/16").

• Length of cord, about 24".