28 SCIENTIFIC CATALOGUE. 



Jellet (John H., B.D.) — a treatise on the 



THEORY OF FRICTION. By John H. Jellet, B.D., 

 Senior Fellow of Trinity College, Dublin ; President of the Royal 

 Irish Academy. Svo. 8s. 6d. 



The Theory of Friction, considered as a part of Rational Mechanics 

 has tut, the author thinks, received the attention which it deserves- 

 On this account many students have been probably led to regard 

 the discussion of this force as scarcely belonging to Rational 

 Mechanics at all ; whereas the theory of friction is as truly a part 

 of that subject as the theory of gravitation. The force with which 

 this theory is concerned is subject to laws as definite, and as fully 



susceptible of mathematical expression, as the fo??e of gravity. 



This book is taken up with a special investigation of the laws of 

 friction ; and some of the principles contained in it are believed to 

 be here enunciated for the first lime. The work consists of eight 

 Chapters as follows : — I. Definitions and Frinciples. II. Equili- 

 brium with Frictions. III. Extreme Positions of Equilibrium. 

 IV. Movement of a Particle or System of Particles. V. Motion 

 of a Solid Body. VI. Necessary and Possible Equilibrium. VII. 

 Determination of the Actual Value of the Acting Force of Friction. 



VIII. Miscellaneous Problems —I. Problem of the Top. 2. Friction 



Wheels and Locomotives. 3. Questions for Exercise. " The book 

 supplies a want which has hitherto existed in the science of pure 

 mechanics. " — Engineer. 



Kirchhoff (G.)— researches on the solar spec- 

 trum, and the Spectra of the Chemical Elements. By. G. 

 Kirchhoff, Professor of Physics in the University of Heidelberg. 

 Second Part. Translated, with the Author's Sanction, from the 

 Transactions of the Berlin Academy for 1S62, by Henry R. 

 Roscoe, B.A., Ph.D., F.R.S., Professor of Chemistry in Owem 

 College, Manchester. Part II. 4to. 5.)'. 



"It is to Kirchhoff we are indebted for by far the best and most accuratt 

 observations of these phenom ,-.' Edin. Review. " This memoir 

 seems almost indispensable to every Spectrum observer." — Philo- 

 sophical Magazine. 



Lockyer (J. N.)— ELEMENTARY LESSONS IN AS- 

 TRONOMY. With numerous Illustrations. By J. NORMAN 

 Lockyer, F.R.S. Ninth Thousand. i8mo $s. 6d. 



