444 Notices respecting New Boohs, 



to reflected light certain comets emitted light characteristic of 

 carbou vapour, aud who later by photography in 1881 detected 

 the bands of cyanogen, showing the presence of both carbon and 

 nitrogen. From this important discovery he deduced an intimate 

 relationship between comets and meteors. 



In the section dealing with the Sun and corona Sir William 

 gives one of the earliest detailed descriptions of the spectrum of a 

 •sun-spot. The method proposed by Sir William for viewing the 

 spectrum of the solar prominences without an eclipse being quite 

 correct in principle, it was a disappointment that non-success 

 attended his efforts to see it until after the identity of the principal 

 lines had been recognized at the eclipse of the Sun in 1868. But 

 he was the first to observe and draw the complete form of a pro- 

 minence in full sunshine by the spectroscopic method. The papers 

 on the form and nature of the corona are especially full of profound 

 reflexion and insight ; and the attempt to photograph it in full 

 sunshine is a striking instance of patience and ingenuity, though 

 the task proved too difficult for accomplishment. 



Nor were the Moon and planets neglected, and much careful 

 attention was devoted to the spectrum of Mars and the examination 

 of the absorption lines in it, indicating the presence of water 

 vapour — although this latter is still in doubt. 



One of the difficulties which Sir William had to surmount before 

 he could even begin his work on the chemical analysis of the stars 

 is brought home to the reader in the section on Chemical Spectra. 

 "At that time (1863) no convenient maps of the chemical spectra 

 were available, and to meet this want I devoted a great part of 

 1863 to mapping the spectra of twenty-six of the elements.'"' The 

 results are shown in two plates and a table. 



For the greater convenience of the reader, the Papers have been 

 arranged primarily in order of subject matter, secondarily in each 

 division in the order of their publication, although in a few cases 

 this arrangement necessitates the occasional dividing up of a 

 paper. 



In conclusion, attention should be drawn to the many scientific 

 illustrations accompanying the text, and the two fine portraits of 

 the distinguished author and the gracious lady who since 1875 has 

 shared his labours. 



Lecons sur les Milages metalliques. Par J. Cayalier. 

 Paris : Yuibert et JNony, 1909. 



The aim of the author of this book has not been to bring 

 together the known facts of all metallic alloys ; but to write a 

 treatise, suitable for teaching purposes, which explains the principal 

 methods of investigation, and illustrates them by examples. The 

 volume is divided naturally into two parts. The former deals 

 with generalities such as the modes of preparation of alloys 

 and the study of them in their chemical, metallographic, and 



