SCIENCE— ADVERTISEMENTS 



A Synopsis of the 



Aphididac of California 



By ALBERT F. SWAIN 



22} pages. 17 plates* Papef^$2.25 



Other Recent Publications 



Calendars of the Indians north of Mexico, by lycona 



Cope $ -75 



The Effect of Several Types of Irrigation Water on 

 the Ph Value and Freezing Point Depression of 

 Various Types of Soils, by D. R. Hoagland and 

 A. W. Christie 20 



Notes on the Natural History of the Bushy-tailed Wood 



Rats of California, by Joseph Dixon 25 



Geologry of a Part of the Santa Ynez River District, 



Santa Barbara County, CaL, by Wm. S. W. Kew .25 



The Marine Algae of the Pacific Coast of North Amer- 

 ica. Part I. Myxophyceae, by William A. Set- 

 chell and Nathaniel Ivyon Gardner 1.50 



The University of California Press 



Berkeley, California 280 Madison Ave, New York 



Popular in Universities and Colleges 

 McPHERSON and HENDERSON 



General Chemistry 



A comprehensive survey of general 

 chemistry, the material being 

 limited to that which experience 

 has shown to be within the ability 

 of the average college student to 

 assimilate properly. One of the 

 few most widely used of college 

 chemistries. 



GINN AND COMPANY 



70 Fifth Avenue 

 New York 



LAMP AND SCALE 

 REFLECTION INDICATOR 



OF A NEW AND IMPROVED TYPE 



This outfit is supplied with a small transformer 

 for attachment direct to ordinary lighting circuit 

 of 60 cycles, 110 volts. An automobile headlight 

 lamp and focusing lens insure a spot of higher 

 brilliancy and finer definition than has heretofore 

 been offered. The spot is easily visible in direct 

 sunlight, making it valuable for lecture demon- 

 stration use. 



Also supplied without transformer, for use on 

 D.C. circuit. 



Described and listed in Catalog No. 16. 

 Write for it. 



We have at last caught up with orders for this 

 apparatus and can now make prompt deliveries. 



PYROLECTRIC INSTRUMENT CO. 



ELECTRICAL PRECISION INSTRUMENTS 

 636-640 EAST STATE STREET TRENTON, N. J. 



E. F. NORTHRUP, PRESIDENT AND Technical adviser 



