SCIENCE 



New Series. 



Vol. XXI. No. 540. 



rt 



Friday, May 5, 1905. 



Single Copies, 1.5 Cts. 

 Annual Subscription, 85.00. 





Write for " Biddle's Bulletin " 



It is full of interesting descriptions and diagrams of physical and electrical apparatus. The articles in 

 it are written from a scientific standpoint with the idea of bringing out clearly not only the features of the 

 workmanship, but also the principles involved in the apparatus we handle. 



The April number isjust off the press and upon request will be mailed free to any address 



JAMES G. BIDDLE, 1114 Chestnut Street, Philadelphia 



Special Agent for : Weston Electrical Instrument Co., Electric Storage Battery Co., Siemens & Halske, Otto Wolff', 

 Cambridge Scientific Instrument Co., Hartmann & Braun, Societe Genevoise, Nalder Bros., Kelvin ct James White, etc. 



11 Send for our recent Conchological Bvlletiiis, giving complete price- 

 ^^J-I.ilCXx» lists of our stock in certain interesting families of molluscs, especially 

 ^^^^^^^^^^^^^^ those of which we have many rare forms. Mailed free on request. 

 Lists now ready cover Cypr^a, Conds, Murex, Voluta, Strombus, Cassis, etc. 



WARD'S NATURAL SCIENCE ESTABLISHMENT (Shell Department), Rochester, N. Y. 



The Insulation of Electric Machines r»dy 



BY 



Harry 



Turner 



AND 



Henry 



Metcaee 



HOBART 



With I02 



Illustrations 



Cloth, $4.SO 



" This is the first book to be pubUshed on 

 this most important subject ... to both 

 the designer and the operator of electrical 

 apparatus, as nine-tenths of the ultimate 

 breakdowns in electrical machinery are due 

 to the breakdown of the insulation, no mat- 

 ter' wdiat the primary cause of the trouble. 

 The work of Turner and Hobart is, there- 

 fore, ver}' timely and ... a most valu- 

 able contribution to the subject, giving, as it 

 does, the first logical and comprehensive 

 outline of the general subject . . . The 

 bibliography in one of the final chapters 

 will be found of special value to those who 

 wish to study the subject further." 



— Elccfricdl Kcricir. 



The lYIacmillan Company, Publishers - ■ - 64-66 Fifth Avenue, New York 



