﻿8(U- Notices respecting New Boohs. 



substitute for Newton's Laws of Motion a more logical series of 

 enunciations. Professor Gray makes not the least' reference to 

 these discussions. He explains simply the meanings of the Laws, 

 and in his seventh chapter gives a remarkable and original series 

 of applications of the principles to such practical questions as the 

 efficiency of brakes, the dynamics of self-propelled vehicles, the 

 effect of small periodic variations on the motion of a carriage or 

 ship, etc. In his chapter on general dynamical methods, Professor 

 Gray develops the methods associated with the names of Lagrange, 

 Hamilton, Jacobi, Kelvin, Bertrand, and others, giving a clear 

 account of the distinction between holonomons and not holonomous 

 systems. By restricting himself to the more elementary modes of 

 treatment, Professor Barton gains space for more detailed study of 

 the statics of rigid bodies, which will commend the book more 

 especially to engineering students. He has also a chapter on 

 mechanisms. These remarks may suffice to show that, although 

 they have much in common, the books are markedly distinct. 

 Each has its merits ; and when due regard is paid to the aims of 

 the authors the demerits, if there be any, are negligible. 



Recent publications of the U.S. Coast and Geodetic Survey 

 include : — 



(a) Distribution of the Magnetic Declination in the United States for 



January 1, 1910. 



(b) Results of Observations made at the... Magnetic Observatory at 



Vieques, Porto Rico, 1907 and 1908. 



(c) Results of Observations made at the... Magnetic Observatory at 



Baldwin, Kans., 1907-09. 



(d) Results of Magnetic Observations made... between July 1, 1910, 



and June 30, 1911. 



In (a.) there is a large size declination chart, showing the 

 isogonals (lines of equal declination) and lines of equal rates of 

 secular change for the epoch considered. There are also particulars 

 of secular change for previous epochs at a number of stations. 



The records of magnetic observations — diurnal inequalities, 

 copies of magnetic storms, etc. — in (b) and (c) follow the same 

 lines as in previous years. The most notable special events which 

 they chronicle are that the Vieques Observatory has been moved 

 to new quarters at a small distance from the original ones, and 

 that the Baldwin Observatory has been discontinued and the 

 instruments transferred to a new observatory at Tucson, Arizona. 

 (d) gives particulars of a year's field work carried out by the 

 magnetic ol servers of the American Survey. The land stations 

 occupied numbered 351, about a quarter being "repeat" stations, 

 used for the determination of secular change. The positions of 

 the stations are described, as well as the results of the observations 

 at each. At sea the observations taken by the surveying vessels 

 numbered 85, the majority being taken on the Pacific Ocean. 



