Mr. Edward Arnold's List of New Books 13 



THE BECQUEREL RAYS AND THE 

 PROPERTIES OF RADIUM. 



By the HON. R. J. STRUTT, 



FELLOW OF TRINITY COLLEGE, CAMBRIDGE. 



Demy Svo. With Diagrams. 8s. 6d. net. 



The extraordinary properties of radium have excited so much 

 interest, not only in the scientific world, but also among the public 

 at large, that a clear and accurate account of radio-activity will, it is 

 believed, be generally welcomed. The amount of elementary 

 scientific knowledge assumed to be possessed by the reader has been 

 confined to the smallest limits, and in the case of those parts of the 

 subject which cannot be satisfactorily treated without the use of 

 mathematical symbols the premises and results of the calculations 

 are given verbally in the text and the calculation itself in an 

 Appendix. 



ASTRONOMICAL DISCOVERY. 



By HERBERT HALL TURNER, D.Sc., F.R.S., 



SAVILIAN PROFESSOR OF ASTRONOMY IN THE UNIVERSITY OF OXFORD. 



Demy 8vo. With Diagrams. IDS. 6d. net. 



In these lectures, written for delivery before the University of 

 Chicago, Professor Turner traces the history of modern Astro- 

 nomical Discovery, first showing by what an immense amount of 

 labour and patience most discoveries have been made, and then 

 describing in detail many of the more important ones. Among his 

 topics are Uranus, Eros, and Neptune, Bradley's discoveries of the 

 aberration of light and the nutation of the earth's axis, the photo- 

 graphic measurement of the heavens, Schwabe's work on the sun- 

 spot period, and Mr. Chandler's discoveries in connection with the 

 Variation of Latitude. In spite of the technical nature of the 

 subject, Professor Turner writes with so much clearness that the 

 general reader will find the book no less interesting than will the 

 astronomer. 



