310 Notices ri&pecting New Boohs. 



than the half estimated co-latitude a,s the side b in the other 

 triangle is l$s& than the half estimated co-latitude. We therefore 

 take the Tables and find, by aid of a pair of compasses, two places 

 somewhere in one of the columns headed ' b,' one of which is as 

 much above the level of the half estimated co-latitude as the other 

 is below that level, aud such as to have two numbers opposite to 

 them iu the ' co-hyp ' column approximately agreeing with the de- 

 clination and altitude respectively. The numbers level with these 

 in the adjoining column ' A ' will then agree with the hour-angle 

 and azimuth." 



In the Rules which are appended to the Tables a full account is 

 given of how to find the exact position by means of the intersection 

 of two Sumner lines, or of one Sumner line with the true bearing 

 of an object whose position is known. 



Believing as we do that Sumner's is the only scientific method 

 of treating observations of the sun and stars at sea, and that its 

 general adoption by sailors is a reform much to be desired, not 

 only because of the practical merits of the method, but also, and 

 perhaps chiefly, on account of its leading those who use it to inquire 

 into the reasons of what they do, we welcome this volume as form- 

 ing an important addition to the already heavy debt which the 

 scientific navigator owes to Sir William Thomson. 



Railway Appliances A Description of details of Railway Con- 

 struction subsequent to the completion of tlie Earthworks and 

 Structures including a short notice of Railway Rolling JStocJc By 

 Johis" Wolfe Bakry Member of the Institution of Civil 

 Engineers With Illustrations. London : Longmans, Green <fc 

 Co. Small 8vo, pp. 299. (Text-Books of Science.) 



This work can hardly be regarded as a " Text-Book of Science j" 

 and it occurs oddly enough in a series which is designed — amongst 

 other ends — for the use of boys in Public Schools. However, that 

 is but a small matter ; for it is a book which (we doubt not) will 

 greatly interest the reading public. We all travel by railway, and 

 see, but by no means understand, a variety of mechanical con- 

 trivances used in connexion with locomotion — signals, of which we 

 only know that they are intended to convey information to some- 

 body — handles, of which we only know that they are to be pulled. 



Mr. Barry comes in and enlightens us on all these points ; tells 

 us how the permanent way is formed ; describes the various kinds 

 of sleepers, chairs, and rails, and the ways of fastening them to- 

 gether; discourses of points and crossings, signals, and train- 

 describers, turn tables, and traversers. He discourses of stations 

 and their varieties, whether terminal or roadside, whether for pas- 

 sengers or for goods, and fully sets forth every contrivance con- 

 nected with them. He shows how those familiar objects the Pad- 

 din gton, Euston, and Cannon-Street Stations illustrate the general 

 principles of railway arrangement ; all three are good, in his 

 opinion, though, if we may hazard a conjecture, Cannon-Street is 

 the station he loves best. 



Often as the reader must have been at that famous station, the 

 following particulars will probably be new to him. The minimum 



