20 



SCIENCE 



[Vol. IV., No. 74. 



wishing to understand the applications of elec- 

 tricity must first acquire a thorough knowledge 

 of the theory. Having secured this, he will find 

 no trouble in reading any works devoted to the 

 practice of electrical engineering. 



AMERICAN COASTER'S NAUTICAL 

 ALMANAC. 



The American coaster's nautical almanac for the year 

 188 Jp. Published by authority of the secretary 

 of the navy. Washington, Bureau of navigation, 

 1884. 158 p. 8°. 



It has long been customary for the principal 

 dealers in chronometers, hydrographic charts, 

 and navigation supplies generally throughout 

 the country, to publish annual!}', in cheap 

 pamphlet form, certain of the fundamental 

 data required in the navigation of ships, and 

 compiled largely from the publications of the 

 1 Nautical almanac ' office. Such small prints 

 have commonly been disposed of for a few 

 cents per copy, or given aw a} 7 to masters of 

 vessels, as the tabular data were so scattered 

 among advertisements of the wares of these 

 dealers as to render their distribution a matter 

 of interest to the publishers. 



The recent action of the superintendent of 

 the ' Nautical almanac ' office, in beginning the 

 regular issue of the ' American coaster's nau- 

 tical almanac,' will, it is to be hoped, put an 

 end to this unauthorized extraction from the 

 publications of the scientific offices of the gov- 

 ernment ; for the new annual will contain, in 

 a compact and convenient form, the ephemeral 

 data of every sort required by navigators 

 along the American Atlantic coast, and is 

 issued under the official sanction of the sec- 

 retary of the navy. The ' Coaster's almanac ' 

 is made up from data already in good part 

 accessible to navigators in one form or an- 

 other, but which are now, for the first time, 

 brought together into a single small vol- 

 ume, obtainable with little trouble and ex- 

 pense. 



We have first the elements pertaining to the 

 position, motion, and apparent magnitude of 

 the sun, together with the equation of time, — 

 all given for Greenwich noon, as in the lar- 

 ger annuals of the same office. Following are 

 the times of the moon's phases, — where, by 

 the way, the meridian is omitted, and a doubt 

 is likely to arise whether they rnay not be ap- 

 plicable to some meridian other than Green- 

 wich, — underneath which we find the sidereal 

 time of mean noon, and blank columns left for 

 the navigator to enter with eveiy day the 



necessary data regarding his chronometer, and 

 the latitude and longitude of his vessel at 

 noon. The next succeeding pages contain the 

 positions of a hundred and lift} 7 fixed stars for 

 the beginning of the year, followed by a table 

 for finding the latitude by an observed altitude 

 of Polaris, and a table for converting solar into 

 sidereal time. A matter of some account is 

 the omission from this portion of the ' Coaster's 

 almanac ' of all data regarding the planets. 

 A half-dozen additional pages would have suf- 

 ficed to give the positions of the four bright 

 planets ordinarily employed by navigators, 

 with precision enough to make them quite as 

 useful as the list of star-positions. 



The astronomico-nautical data occupy near- 

 ly fort} 7 pages, or about one-fourth of the en- 

 tire book. Following are twenty pages of tidal 

 data, compiled from the complete tide- tables 

 published by the office of the coast and geodet- 

 ic survey. The approximate predicted times 

 of high water at the principal ports on the 

 Atlantic coast of the United States are given 

 for every day of the year ; while, for inter- 

 mediate ports, tables of tidal constants are 

 added. The times of high water are reduced 

 to the standards of the eastern and central 

 meridians, respectively five hours and six 

 hours slow of Greenwich time. 



We have next a very comprehensive list of 

 more than five hundred lighthouses, lighted 

 beacons, and floating lights, on the Atlantic 

 and Gulf coasts of the United States, occu- 

 pying thirty-five double pages, and giving 

 the name, location, characteristic, and order 

 of each light ; also the geographical posi- 

 tion, height above the sea-level, maximum 

 distance at which visible, the color and pecul- 

 iarity of the lighthouse or vessel, and the char- 

 acter of the accompanying fog-signal. This 

 is followed by a ten -page list of lights in 

 the West-India Islands, and on the adjacent 

 coasts, the coast of Brazil, etc., to the Ma- 

 gellan Straits, similar data being likewise 

 given for these lights. The ' Coaster's alma- 

 nac ' concludes with nautical directions for 

 manoeuvring in, and avoiding the centre of, 

 cyclones in the North Atlantic ; the twenty- 

 six articles of the revised international regula- 

 tions for preventing collisions at sea ; general 

 information regarding life-saving stations, with 

 instructions to facilitate the shipwrecked mar- 

 iner in receiving the assistance of these sta- 

 tions ; and, fin all}', descriptions and explana- 

 tions of the signals displayed by the army 

 signal-service as cautionary against approach- 

 ing storm, severe winds, and rough weather 

 generally. 



