Page:Popular Science Monthly Volume 16.djvu/210

 in which it is eminently proper a sailor should be untrammeled. No, a track-chart is a useful auxiliary—it partly solves the problem of tracing the best course from port to port, and such a chart will eventually form part of the entire set; but a full exhibition of all the data on which the judgment is based is essential to every intelligent seaman.

It is the log-books of ships of our own navy from 1855 to 1877—the large accumulation of twenty-two years—that are now undergoing compilation at the Hydrographic Office for the series of charts described: since 1877, by an order of the Navy Department, the compilation is made by the navigator of each cruising ship. Being an officer of many years' experience at sea, and having direct and daily supervision of the log-book, there is great advantage in having the data arranged in the requisite form, on the spot and at the time of its occurrence, by such a competent person.

Both the observations and compilations are made with a definite object in view, and, as that is to furnish charts for their future guidance, it is an incentive to the officers engaged in their preparation to make them as trustworthy as possible. The compilation is to continue until charts for all the frequented portions of every ocean are published.

When a log-book is full, both it and the compilations are sent to Washington, where they are examined, compared, and used as found necessary.

In an article in a former number of this magazine, I have said that it is impossible to predict, as is done on the land, what the weather will be in various parts of the ocean for any short period; there we lack the stationary points of observation with direct and instant communication: as pointed out by Maury, the most that can be done in this way is to warn European countries by telegraph of the approach of storms that traverse the Atlantic from the American Continent; and of late this has been successfully done by the "New York Herald."

In conclusion, I will merely allude to the utility of the charts that form the subject of this article. If, on land, it be optional to choose one's residence according to the salubrity of the climate, so at sea, the mariner, with a panorama of the winds and weather spread before him, can direct his course through only those squares that are favorable and avoid the stormy.

Moreover, the novice to the sea or the philosopher in his study can, by a mere inspection of them, see what has passed over the waste of waters during the last hundred years, and be more fully and accurately informed regarding what in all probability he would have to encounter, in the way of aerial phenomena in an ocean-voyage, than the most weather-beaten tar that plows the main.