Notices respecting New Boohs. 347 



curves, and of curved surfaces, and closes with an exposition of 

 the relation between the method of perspective and that of 

 Monge. Chapters III. and IV. are each provided with appro- 

 priate exercises. The last chapter of this exceedingly useful and 

 fascinating Tract is dedicated to the so-called Photogramnietry or 

 Metrophotography, whose aim is to obtain from photographs a 

 correct metrical representation of the object photographed. 



2. Contains a collection of useful hints for the practical pro- 

 cesses of Interpolation and Numerical Integration. The first 

 two chapters give some theorems in the Calculus of Finite Differ- 

 ences, and formulae of Interpolation, e. g. those of Lagrange, 

 Newton, Stirling, Grauss, and Eessel. The subject is illustrated 

 by numerous concrete examples. Chapter III. treats of the con- 

 struction and use of Mathematical Tables. Many mathematical 

 and physical students will be particularly grateful to the author 

 for that chapter, in which they will fiud details on the subject, 

 otherwise not very accessible. The last chapter of this very 

 useful " Course " is dedicated to Numerical Integration. 



3. Professor Conway gives in the four chapters of " Belativity " 

 the substance of his four lectures delivered before the Edinburgh 

 Mathematical Colloquium : I. Einstein's Deduction of Fundamental 

 delations. II. Transformation of Electromagnetic Equations. 



III. Applications to Eadiation and Electron Theory, — with a 

 short investigation concerning relativistic dynamics (pp. 28-34). 



IV. Minkowski's Transformation,— containing a very short expo- 

 sition of Minkowski's " geometrical " representation of the Lorentz 

 transformation, and of the meaning and use of Minkowski's 

 four- and six-vectors. This little u Tract " can. be recommended 

 as a rapid but easily intelligible introduction to the theory of 

 relativity. 



4. The object aimed at by the authors is " not to discuss the 

 series of Fourier from the theoretical standpoint, but rather to 

 provide what is necessary for the practical application of the 

 subject." Chapter I. contains generalities on Fourier's Theorem, 

 illustrated by a number of useful and elegant examples. From 

 Chapter II. the reader learns the art of the practical evaluation of 

 the coefficients of a Fourier expression ; here the 12-ordinate 

 and the 24-ordinate Arithmetical Methods are fully explained, a 

 concise computing form, devised by Prof. Whittaker, is annexed, 

 and an account of Perry's, Wedmore's, Harrison-Ashworth's, and 

 Beattie's graphical methods is given. Chapter III. is dedicated 

 to Periodogram Analysis, a subject which "has not received 

 adequate treatment hitherto in any English text-book." This 

 chapter will be very helpful to the physicist, as well as to 

 the astronomer and meteorologist. The last chapter is a brief 

 introduction to Spherical Harmonic Analysis. The exposition of 

 the subject is based on Whittaker's general solution of Laplace's 



