Literary Notices. 233 



components of Castor are put down as between two and three 

 seconds apart, while Engelmann's measure gives 5"526 ; S Herculis 

 and comes are given as between seven and eight seconds apart, 

 which is surely much too little. 



Elementary Treatise on Physics, Experimental and Applied. 

 For the use of Colleges and Schools. Translated and Edited from 

 Ganot's Elements de Physique (with the author's sanction), by E. 

 Atkinson, Ph.D., F.C.S., Professor of Experimental Science, Royal 

 Military College, Sandhurst. Second edition, revised and enlarged. 

 Illustrated by a coloured plate, and nearly 700 woodcuts. (Bailie re). 

 Part II. — In a notice of the first part of the new edition of this 

 excellent work we expressed a decided opinion that it is the best 

 book of the kind which has appeared. To that opinion we adhere, 

 though there are some minor points in which Professor Atkinson 

 ought to have improved upon the original. Thus, at p. 447 we are 

 told that the new silvered glass mirror telescopes " are much shorter 

 than the old ones, their focal distance being only about six times 

 the diameter of the mirror." The celebrated Short made his 

 ' dumpy' metallic telescopes with focal lengths as short as have been 

 given to any successful glass ones, and it is incorrect to say that the 

 usual focal length of fine glass silvered telescopes is only six times the 

 diameter of the mirror. The figure given of the mounting (p. 448), 

 though pretty looking, is bad — very inferior to Mr. Browning's 

 pattern, and students will be misled who suppose from M. Ganot's 

 work that a 6^ inch mirror should only bear a magnification of 150 

 to 200. One of that size in our possession, the mirror by With, and 

 the mounting by Browning, bears from 600 to 700 well on bright 

 objects. The microscope in this part fares worse than the telescope. 

 Instead of figuring a good instrument by one of the great English 

 makers, a very poor one by Chevallier is represented, giving no idea 

 of the best constructions, and nothing is said concerning the 

 formula of the best objectives. These, however/are trifles in com- 

 parison to the general merit of the work, but they ought not to be 

 passed over. 



The Birds op Middlesex ; a Contribution to the Natural History 

 of the County. By James Edmund Hasting, F.Z.S. (Van Voorst.) 

 — A very pleasantly written work, giving accounts of the birds 

 habitually living in, or visiting Middlesex. Mr. Hasting has judi- 

 ciously left technical descriptions and systematic information to be 

 obtained from well-known ornithological works. His remarks are 

 thrown under heads corresponding with the principal divisions of 

 birds into orders and families, and frequently enlivened by good 

 anecdotes. For example, a very interesting account is given of a. 

 black-backed gull, caught and tamed by the author : — " A curious 

 fact with regard to this gull is that he catches sparrows for himself 

 very dexterously, and the way in which he does it is this. About 

 the time that the fowls are being fed, he makes his way to the 

 poultry-yard, and mingling with the hens, walks very slowly about 

 with his head drawn in so as to make his neck look very short, and 

 as if, in fact, he were trying to look as much like a fowl as possible. 

 As soon as the general rush for grain is over, the sparrows drop 



