22 THE AMERICAN MONTHLY [Jan., 



subsequently, on the part of naturalists as to the methods 

 of investigation employed. To gratify this he under- 

 took a second treatise on the methods of comparative 

 anatomy, in which, among other instruments, are figured 

 two microscopes which appear to me to present the 

 earliest type, regard being had to date, of the Continen- 

 tal stand. 



The work of dissecting small animals requiring the 

 alternate use of the simple and the compound microscope 

 with as little disturbance as possible of the preparation, 

 together with its arrangement in a convenient form for 

 manipulation, we find this point particularly studied in 

 the design of these two stands : firstly, by the intro- 

 duction of a rotary stage ; secondly, by a limited height 

 and a vertical position of the model. A precise account 

 of his claims to this invention is to be found in a letter 

 written by Strauss-Durckheim in 1850 to the optician 

 Chevalier, which is printed in the life of the latter by 

 his son ; from it I quote the following paragraphs : 



" Having formerly had to occupy myself a good deal 

 with anatomical researches on very small animals with a 

 microscope, which by a kind of chance, was of small 

 dimensions, I did as other microscopists do, I tried to 

 make the best of it by perfecting the mechanical part by 

 several means which necessity suggested to me, and re- 

 flecting on all the inconvenience which I had encountered 

 in my microscopical researches during my long exper- 

 ience, I finished by designing one of these instruments 

 in which all difficulties were removed, and this was the 

 microscope of which I published the description in my 

 work on the art of dissecting which I mentioned above " 

 (the Treatise on Comparative Anatomy, published it 1842, 

 this being written in 1850). 



He continues, "The first requisite of the microscope is 

 to have in all about 3 dm. ( - 12 inches) in height, so 

 that the observer, comfortably seated at the table at 



