and was the very modest beginning of what he afterwards issued as "Sailing Directions", which eventually grew to the enormous size of 1257 pages in two volumes in quarto. The purpose of the little pamphlet was to interpret the meaning and the significance of the wind and current chart which had recently been issued, and to furnish instructions to navigators for the proper keeping of the abstract log on their voyages. They were to enter in this log the latitude and longitude every day at noon; the hourly rate of the currents expressed in knots; the variation of the compass; the reading of the thermometer, in both air and water, at nine o'clock each morning; the state of the barometer just before, during, and just after a gale of wind with the changes and time of changes in the direction of the wind during the gale; careful entries as to the direction and force of the winds every eight hours; and other marine phenomena such as whales, flocks of birds, rains and fogs, etc., etc. When properly filled out, these logs were to be sent to Maury at the Observatory where the information would be tabulated. It was also suggested that tightly corked bottles containing the latitude and longitude, and the date be thrown overboard at stated times, and that such floating bottles be picked up when seen, and the place and time be carefully noted in the abstract log. Those who agreed to cooperate in these various ways were to receive free of cost a copy of the "Wind and Current Chart of the North Atlantic".
Maury predicted confidently that, by following his directions, the average 55 days' voyage from New York to Rio by the old route might be shortened by from 10 to 15 days. This prediction was fulfilled by the barque W. H. D. C. Wright of Baltimore, which early in 1848