Geology and Mineralogy. 57 



ployed: — (1st) The mean declination for the day at which the 

 inferior or superior conjunction in the case of the inferior planets, 

 or conjunction or opposite in the case of superior planets, takes 

 place is compared with the mean declination for neighboring days 

 or for the month. (2d) By means of the mean value of the secu- 

 lar change for the period 1873-1885 the value of the declination 

 for the time of conjunction, etc., is compared with the actual value. 

 (3d) The value oi the diurnal range at conjunction, etc., is com- 

 pared with the mean value. Although the differences obtained 

 are excessively small, amounting as they do to only a fraction of 

 a minute of arc, and large as is the probable error, the author con- 

 siders that the numbers obtained point to the planets being so 

 highly magnetized that they are capable of affecting the magnet- 

 ism of the earth to an extent which is recognizable with the mag- 

 netographs now in use. — JPhys. Soc. Abstracts, Nov., 1895. 



16. Molecules and the Molecular Theory of Matter, by A. D. 

 Risteex. 223 pp. Boston and London, 1895. (Ginn & Com- 

 pany.) — 'This popular and yet scientific presentation of the 

 accepted molecular theory of matter with reference to solids, 

 liquids and gases, will aid many to gain a clear idea of a difficult 

 subject and one which has not been written out before in con- 

 nected form. The language is for the most part simple and the 

 illustrations numerous and helpful. The volume is based upon a 

 lecture delivered a year since and the same form of address has 

 been maintained in the expanded work ; it may be questioned 

 whether this is an advantage. 



17. School Physics: a new text-book for high schools and 

 academies, by Elrot M. Avert. 608 pp. New York and Chi- 

 cago. (Sheldon & Company.) — This new edition of Avery's 

 Physics is commendably fresh in matter, introducing many new 

 topics and new applications of physical principles. At the same 

 time, it retains the good features of earlier editions, conspicu- 

 ously clearness of style and arrangement, and liberality of illus- 

 trations and of exercises and problems. In the hands of a good 

 teacher, properly equipped as to laboratory apparatus, it should 

 produce excellent results. 



II. Geology and Mlnekalogy. 



1. Reconnaissance of the Gold Fields of the Southern Appala- 

 chians ; by George F. Becker, Ann. Rep. U. S. Geol. Surv. 

 1894-5, Part III. (Abstract prepared by the author.) — This 

 report is based on field work done in 1894. Besides due refer- 

 ence to the results obtained by earlier observers in the same field, 

 it also contains a digest of the literature dealing with the 

 gold deposits of the maritime provinces and the Green mountains, 

 the purpose being to present in one paper the most noteworthy facts 

 concerning the occurrence of gold on the entire eastern side of the 

 continent. In the northern portion of this region gold has been 

 found in important quantities in Nova Scotia, and a considerable 



