Notices rejecting New Books. 441 



lision of bodies, and the laws of falling bodies, are generally some- 

 what difficult questions for boys, but they are here made so remark- 

 ably clear and simple that no boy of ordinary intelligence can fail to 

 understand them. All we will add is, that if the boy not only reads, 

 but studies these lessons, and then tries to solve the problems pro- 

 posed therein, his success will be certain ; and it will bring with it 

 so much pleasure and encouragement, that he cannot fail speedily to 

 overcome far greater difficulties. 



The last lessons we shall notice are those by the Rev. Robert 

 Main, on Astronomj", which may also be pronounced successful. 

 The explanations are usually clear, though there are some obscure 

 sentences. For instance, in the following there is surely some mis- 

 print : — " The real motion of the earth from west to east produces an 

 exactly equal apparent motion of the sun in the same direction." In 

 the following there must be some omission : " Since the ecliptic and 

 equator are both great circles, that is, since both pass through the 

 visible sphere of the heavens, their planes will cut each other in a 

 line, which is a diameter of the sphere." We disagree with the in- 

 troductory sentence, too, inasmuch as we cannot understand " why 

 the grandeur of its objects" can make astronomy "the noblest of 

 all physical sciences ; " neither are we aware that astronomers are 

 more " completely separated from the petty cares and concerns of 

 our present existence " tlian other physicists. All this is merely 

 accredited nonsense, usually uttered thoughtlessly, and not worthy 

 of being uttered at all. It forms no part of Mr. Main's lessons, 

 however, which are really good. 



In conclusion, we wish Mr. Hughes every success ; his first book 

 is a good one, and we hope his future books will be better. We 

 have given unusual space to our review because we deem his project 

 an important one, and because it is almost the first of its kind in 

 which the principle has been recognized, that only the ablest men 

 can expound the elements of a science successfully, and that the task 

 is in every respect worthy of their valuable time. 



A Treatise on Conic Sections. By the Rev. George Salmon, A.M. 

 Third Edition. London : Longman, Brown, Green, and Long- 

 mans. 1855. 



It is a source of considerable satisfaction to find, amongst the 

 crowd of very imperfect educational books which are daily issued from 

 our press, a treatise so truly valuable as the present ; and it is also 

 cheering to learn that the public has so far recognized its merits as 

 to demand a third edition. The book is now sufficiently well known, 

 otherwise its title might mislead many ; for although it is true that 

 the greater part of it is devoted to an examination of the properties 

 of the conic sections, yet this being done from an analytical point 

 of view chiefly, it was necessary to prepare the reader by a similar 

 investigation of the properties of the line and circle ; so that, in fact, 

 the whole constitutes a very efficient treatise on the elements of 

 analytic geometry, such as may with advantage be placed in the 

 hands of every student who has mastered the elements of Euclid, 



Phil. May. S. 4. Vol. 10. No. 68. Dec. 1855. 2 G 



