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Journal of Applied Microscopy 



SCBSCRIPTIONS : 



One Dollar per Year. 



To foreign countries, $1.25 



per Year, in adranee. 



Cj^'Subscnbers will be no- 

 tified when subscription has 

 expired. Unless renewal is 

 promptly received the JOUR- 

 NAL will be discontinued. 



Journal of 



Applied Microscopy 



and 



Laboratory Methods 



Edited by L. B. ELLIOTT. 



SEPARATES. 



One hundred separates of 

 each original paper accepted 

 are furnished the author, 

 gratis. Separates are bound 

 in special cover with title. 

 A greater number can be had 

 at cost of printing the extra 

 copies desired. 



With this issue, completing the sixth volume of the Journal of Applied 

 Microscopy and Laboratory Methods, its publication is closed. 



On behalf of the publishers and readers of the Journal, we wish to extend 

 our appreciation to the many contributors and to the department editors who 

 have, continuously and without remuneration other than the knowledge that 

 they were working for the benefit of their co-laborers, supplied the material 

 which has appeared in our pages. 



The editor wishes to extend to the Bausch & Lomb Optical Company, and 

 to Mr. Henry Lomb, through whose generosity the publication has been made 

 possible, his appreciation of their liberality in this connection and of their 

 interest in the advancement of science. \li. 



The publication was begun with the belief, based on extended observation, 

 that as there was no publication in the English language devoted to laboratoiy 

 methods and apparatus, those engaged professionally in laboratory work in 

 colleges, universities, high schools and in the industries, as well as individual 

 workers, would welcome such a publication especially if offered at a moderate 

 price. Experience has shown that the leaders in this work have lent their sup- 

 port to the Journal and have done all they could do to interest others, but the 

 great mass of science teachers, those who are farthest from the great centers of 

 investigation and growth, those who really need and could make daily use of the 

 Journal, and for whom it was primarily intended, have not evidenced as much 

 interest as we could wish. 



However, we believe that the Journal has served a useful purpose, and that 

 the complete volumes on file in the various libraries throughout the world will 

 continue to be useful. That every special line of work is helped by the stimulus 

 of a live periodical is evident, and we trust that, should others begin the publi- 

 cation of a journal for American Microscopy, it will receive the hearty support 

 of all workers. 



QUESTION BOX. 



Inquiries will be printed in this department from any inquirer. 

 The replies will appear as received. 



No. 35. — Kindly give the practical and also the theoretical formula for com- 

 puting the value (focal length) of the supplementary lens for any length of 

 camera extension, and any combination of lenses, eye-piece or tube length as 

 per the Misses Foote and Strobell method of focusing for photo-micrography, 

 as described in the April, 1902, and December, 1902, numbers of the Journal, 

 assuming the eye of operator to be normal and on the bright side of thirty years 

 of age. — D. A. Haling, 89 Cheshire St., Cleveland, O. 



