SCIENCE— ADVERTISEMENTS 



new form of **At- 

 wood Machine," for 

 illustrating the law of 

 Falling Bodies. It 

 makes a graphic rec- 

 ord and is reliable 

 and inexpensive. 



The above, as well as an Interesting variety of 

 other apparatus for Experimental Mechanics, 

 Machine and Steam Engine Models, Mensuration 

 and Geometrical Models, etc., is made by the 

 British firm of Messrs. G. Cussons Ltd. 



We have accepted the American Agency for these 

 Goods and invite inquiries from college pro- 

 fessors, as well as from teachers in Normal, High 

 and Manual Training Schools. 



Material and workmanship are excellent ; and 

 '' Duty-free " prices moderate. 



Write for Circulars 300 and 505 



JAMES G. BIDDLE 



Importer of Highest Grade 

 Scientific Apparatus 



1211-13 Arch St. Philadelphia 



Be sure to visit our Permanent 

 Exhibition 



HEARSON 

 INCUBATORS 



WITH Patent Capsule Teivipera- 



TURE Control, for Gas, Oil 



and Electric Heating 



These utensils are widely used in European laboratories 

 (notably in the Pasteur Institute, Paris, France) and have 

 met with the unqualified approval of all bacteriologists 

 in the United States to whom we have sold them. 



We furnish them in nine sizes for gas heating, 

 five sizes for oil heating, six sizes for electric 

 heating and four sizes for low temperatures. 



Send for illustrated and descriptive pamphlet, with 

 Duty Free and Duty Paid prices 



SOLE U. S. AGENTS 



ARTHUR H. THOMAS CO. 



IMPORTERS AND DEALERS 



Microscopes, laboratory ap- 

 paratus AND Chemicals 



1200 WALNUT ST., PHILADELPHIA, PA. 



