286 The Microscope. 



Cocaine Dosage and Cocaine Addiction— Cocaine Toxaemia. By J. B, 

 Mattison, M. D., Brooklyn, N. Y. Reprint. 



Merck's Bulletin. ' 



This excellent little sheet furnishes a record of new discov- 

 eries in drugs and their application in medicine. From the exami- 

 nation of the copy before us, we should judge it to be of consider- 

 able service in posting physicians in the latest remedies. 



CORRESPONDENCE AND QUERIES. 



643 Broadway, Albany, N. Y., July 3, 1888. 

 To the Editors of The Microscope : 



Gentlemen — Enclosed please find a table of measurements, 

 which I would ask you to kindly give to the readers of The 

 Microscope through its columns — if possible in the next issue. 



As I found that the measurements of the committee of the 

 A. S. M. and mine did not agree, I went to work to investigate what 

 the cause of the variation might be, and this is the result. 



During the last six months I have worked quite a number of 

 days investigating into this matter, and to convince myself that "the 

 difference was caused by the various applications of illuminations, 

 etc., as given in the table. Yours very truly, 



CHAS. FASOLDT, Sr. 



MEASUREMENTS. 



Table showing the variation in measui'ements due to the differ- 

 ent applications of light and illuminations. 



The image of j\ inch was the object on which these 

 measurements were made, and was ruled on a glass disc of No. 2 

 covering glass, yoVit ^^ thickness. 



All measurements were taken on one and the same ruling, with 



the same microscope, objective and eye-piece, under the same focus, 



and having the microscope in the same position continually, and 



only changing the mirror and excluding the one light while the 



other was used. 



unmounted. 



Lamplight. 



Lines Downward. 



Concave mirror, -^^ in rni.liwts ~ 



Plane mirror, f^iu. ttj^.^zttj + 



lU.through objective, -^^ in. xijw.^o^ii + 



Lines Upward. 



Concave mirror, i% in rmy.Trnr + 



Plane mirror, x^^j in W W + 



111. through objective, ^^\n. xffo.g^jj + 



