Notices respecting New Books. li*l 



author at the University of Upsala on the spark-discharge, as 

 affected by the material of the spark-electrodes, the resistance 

 included in the circuit, &c. The results obtained are clearly 

 exhibited in the form of tables and curves. 



La Telegraphie sans Fll. L'GEuvre de Marconi. Traduit du 

 Scientific American de ]N"ew-York. Bruxelles : Eamlot Ereres 

 et Soeurs. Pp. 64. 

 This is a simply written account of the rise and progress of wireless 

 telegraphy, and is a French version of a series of articles in the 

 1 Scientific American.' It is provided with numerous footnotes 

 in which are briefly explained, for the benefit of the non-technical 

 reader, the meanings of the various technical terms employed in 

 the pamphlet. 



Gravitation als Folge einer Umwandlung der Bewegungsform des 

 Aethers im Inneren der wagbaren JIaterie. Von Dr. Hiber. 

 Munchen: H. Lukaschik, 1903. Pp. 44. 

 The author attempts to account for gravitation by assuming the 

 tether to consist of discrete, extremely minute, and somewhat 

 closely-packed particles moving about in a manner similar to that 

 of the molecules of a gas, colliding with the ultimate particles 

 which build up a material atom, giving up some of their energy to 

 them, and receiving the energy back in a different form, with the 

 result that the kinetic energy of the aether particles in the imme- 

 diate neighbourhood of an ultimate material particle becomes 

 reduced, and the material particle becomes surrounded by a sort 

 of atmosphere within which the aether pressure is less than at a 

 considerable distance from the particle. By reason of this effect, 

 two particles at no great distance from each other will be forced 

 towards each other, and this constitutes gravitation. This idea is 

 elaborated by the author, and applied to the explanation of various 

 facts. The pamphlet is entirely non-mathematical, and forms easy 

 reading. 



An Introduction to the Study of Spectrum Analysis. By "W. 

 Marshall Watts, D.Sc, FJ.C. With coloured plate and 135 

 illustrations in the text. London : Longmans, Green & Co. 

 1904. Pp. vih + 325. 

 The subject of spectrum analysis has always possessed a great 

 fascination not only for serious students of physical science, but 

 also for the general reader, whose interest has, no doubt, been 

 considerably stimulated by the popular articles which have appeared 

 from time to time on this subject in leading periodicals. The book 

 before us should, on this account, find a wide circle of readers, for 

 while it contains a good deal that can only be followed by readers 

 having the advantage of a scientific training, yet there are other 

 portions which are capable of being read with interest and intelli- 

 gent appreciation by any person having a good general education. 

 After an introductory chapter containing an account of the 



