The Cruise of the Branwen

THE CRUISE OF THE BRANWEN navigation than are most modern seafarers, for it is worth while remembering that Odysseus could take his latitude without any better instru– ment than a short length of twine, which he would hold up between his eye and the heavens. With one end of it on the Pole-star and the other end on the horizon he could swing it round until it passed through the tail of the constellation called the Bear, and so make a fair guess at his position. The whole process* was suggested (with possible limits of error) by Sir William Thomson (as the late Lord Kelvin was then) in the Mathematical Tripos for 1874-, and his own solution is given in the Educational (]"imes for April 1901 (No. 6707). Odysseus had no "Nautical Almanac," or he might have found out his longitude as well by the same process, taking the moon and some bright star near her as his two points; and it has always been a mystery to me that Nansen, who describes his diffi– culties in getting home after his chronometers ran down, did not employ this ancient method, which would of course become more and more accurate the nearer the observer was to the North Pole. The star we now call the Pole-star could not have been used as we now use it until about five hundred years ago, and it is most interesting to observe that astronomy can give us a suggestion for the date of the Homeric poems which neither Victor Berard nor any other Homeric editor has yet used; for Calypso bade Odysseus keep the Bear " ever on the left as he traversed the deep " towards Greece, and we are told how he saw • These references were kindly given me by Professor Greenhill. 4-4