SCIENCE— ADVERTISEMENTS 



The "Detroit" 

 Combination Gas Machine 



Automatically makes the best 

 and cheapest gas for 



Laboratory Uses of Every Character 



Heating — Cooking — Lighting 

 Over 30,000 in daily use 



Descrlpllce calalogas and names of users In your 

 locality sent on request 



THE DETROIT HEATING & 

 LIGHTING Co. 



612 Wight St. Detroit, Mich. 



Established 18SS 



Publications of 

 Carnegie Institution of Washington 



The publications of the Institution now numher overl 350 

 volumes, the subjects including Anatomy, Archaeology, As- 

 tronomy, Botany, Chemistry, Economics and Sociology, Em- 

 bryology, Experimental Evolution and Heredity, Engineering, 

 Folk-Lore, Geology, History, International Law, Literature, 

 Mathematics, Medicine, Nutrition, Philology, Physics, Zoology. 

 Classified and descriptive lists will be sent postpaid on appli- 

 cation. 



120. Decker, F, F. The Symmetric Function Tables of the 

 Fitteenthic. Quarto, 21 pp 81.25 



245. Hedrick, H. B. Interpolation Tables or Tables of Pro- 

 portional Parts, containing the products to the nearest 

 unit of all numbers from 1 to 100 by each hundredth from 

 01 to 0.99 and of all numbers from 1 to 1000 by each 

 thousandth from 0.001 to 0.999. FoUo, 149 pp $5,00 



250. Knoeel, E. B. Ulugh Beg's Catalogue of Stars, revised 

 from all Persian manuscripts existing in Great Britain, 

 with a vocabulary of Persian and Arabic words. Quarto. 

 109 pp. 1 pi »2.00 



105. Lehmee, D. N. Factor Table for the First Ten Millions, 

 containing the smallest factor of every number not divisible 

 by 2, 3, 5, or 7 between the limits and 10U17000. Folio, 



xiT-t-476pp. Bound in leather and buckram KO.OO 



Unbound 818.00 



165. Lehmer, D. N. List of Prime Numbers from 1 to 



10,006,721. Folio, xvi -1-133 pp $5.00 



43. Peters, C. H. F. Heliographic Positions of Sun-Spots, 

 observed at Hamilton College from 1860 to 1870. (Edited 



by E.B. Frost.) Quarto, siii -1-189 pp $2.50 



SO. Peters, C. H. F., and E. B. Knobel. Ptolemy's Cata- 

 logue of Stars. A Revision of the Almagest. Quarto, iii -1- 

 207 pp S3.50 



All communicationB should be addressed to 



CARNEGIE INSTITUTION OF WASHINGTON 

 WASHINGTON, D. C. 



Are You About To Buy 

 Chemical Apparatus? 



Drop us a line before you buy 

 and we'll try to show you 

 what you may gain from buy- 

 ing from us. 



WE SPECIALIZE IN 

 Graduated and Blown Glassware 

 Thermometers, Hydrometers 

 Coors and Guernsey Porcelain 

 Pyrex Glassware 

 All kinds Filter Paper, Hardware 

 Heavy Separatory Funnels and Kipps 

 Generators and Stains 



Out 500-page catalogue sent upon request 



LENZ APPARATUS CO. 



{Manufacturers — Dealers — Importers 



18 East Sixteenth Street 

 New York City, U. S. A. 



Dial Decade 

 Resistance Boxes 



Single dial boxes of lo coils per dial, of 

 varying total values up to 100,000 ohms. 



They are also furnished in 2, 3, 4, 5, 

 and 6 decades per box. 



Pyrolectric Instrument Co. 



Pyrometric and Electrical Precision 



Instruments. 



636 East State St., TRENTON, N. J. 



E. F. Northrup, President and Technical Adviser 



