MAKING A POINT

* Longitude was calculated by dead reckoning, which accounts for the discrepancies between the positions calculated by the different navigators. Dead reckoning involves putting together the figures for the known course or courses and estimated speed or speeds over a given period of time, and so working out a position in relation to the previous point calculated and pricked off on the chart. Hacer punto, `making a point,' is Columbus's phrase. On a long voyage the possibility for cumulative error on the p art of a man not skilled in estimating speed and leeway was considerable, even when his superior was not deliberately supplying false information.