Miscellaneous /Scientific Intelligence. 283 



als occurring in the pegmatite veins of southern Norway. The 

 first part has now been issued, which includes some of the rarest 

 and most complex species, — namely, those belonging to the niob- 

 ates, tantalates, titanates, and titano-niobates. The descriptions 

 here given leave nothing to be desired and are accompanied by a 

 series of plates, giving figures of the crystals of many species ; 

 there is also a map of tbe portion of Norway involved, showing 

 the position of the localities. 



4. Das Problem der Schioingungserzeugung ; von Dr. H. 

 Barkhausen. Pp. iv + 113. Leipzig, 1907 (S. Hirzel). — The cen- 

 tral idea of this book is that the production of oscillating electric 

 currents may be regarded as due to the variation of resistance, 

 inductance, or capacity in a circuit containing a steady E.M.F. In 

 this way the author classifies all alternating current apparatus 

 from the ordinary generator to the singing arc. He points out 

 analogies between different forms of apparatus, and deduces some 

 general conditions for stability and efficiency. The last section 

 deals with mechanical oscillations and their relations to the elec- 

 trical problem. h. a. b. 



5. Lehigh University, Astronomical Papers. Volume I. 

 Part I. Results of Obsei'vations with the Zenith Telescope of 

 the Sayre Astronomical Observatory from /September 11, 1904, 

 to September 1, 1905 ; by John H. Ogburn. Pp. 46 and Table. 

 Published by the University, South Bethlehem, Pa., 190V. — This 

 paper embraces the results of the first year of latitude observa- 

 tions with the new zenith telescope, the purchase of which was 

 provided for in 1903 by Mr. R. H. Sayre with the general specifi- 

 cation that it should be equal to the best in existence. The 

 description of the telescope, its location, and the scheme of work 

 are outlined in the preface. The instrument is located on the 

 same meridian and 6 7 "08 feet north of the instrument with which 

 Professor C. L. Doolittle carried on his well-known variation of 

 latitude work from 1876 to 1895. 



The residuals from the adjusted latitudes show that the mean 

 probable error of a single observation was //- 121. The constant of 

 aberration derived from the whole series for 11)04-5 is 20" , 4645± 

 0"-01098. The extreme variation of latitude shown is from 

 40° 36' 23"-7l3 on Feb. 21, 1905, to 40° 36' 24"'007 on Aug. 24, 

 1905. Plotting the final latitudes obtained at intervals of from 

 three to five weeks and drawing a smooth curve between the 

 points, it is seen that the final latitudes mostly lie not more than 

 //- 01 from the curve and in no case more than //# 04 from it. 

 When it is considered that these figures amount on the surface 

 of the earth to but one foot and four feet respectively, the accu- 

 racy with which modern astronomy can follow the wanderings 

 of the earth's axis within its body is perceived. The author is 

 to be congratulated on the success of the arduous work of obser- 

 vation and reduction performed without assistance and in addi- 

 tion to the usual duties of college instruction. j. b, 



