Some of the readers of the Institute's Journal may be amused at the following experiences in navigation, which I had fifteen years ago. In February 1942 I was crossing the Atlantic from Halifax N.S. to Liverpool in a convoy, and the passengers were of course never told anything about our position from day to day. I had no instruments, and not even a table of logarithms or of sines and cosines, but I did have much leisure and a good supply of blank paper, and I occupied myself by trying to find out where we were. On two occasions I told my estimates to the Chief Officer of the ship, who was not allowed to make any answer at the time, but on each occasion four or five days later he told me how far I had been from the true position.