1871.] 387 [Hagen, 



tion, which was seconded by Prof. Agassiz and unanimously 

 adopted : — 



Resolved: That the Boston Society of Natural History, having 

 received information of the destruction of the Collections, Library and 

 Building of the Chicago Academy of Sciences during the recent devas- 

 tating fire, hereby offers its sympathy to the Academy in this, its sec- 

 ond trial by fire, with the promise of a series of its publications, and 

 such duplicate specimens as may prove acceptable, when the Academy 

 is prepared to receive them. 



The thanks of the Society were voted to Mr. John J. 

 Glover, for a fine mounted specimen of the male peacock, 

 JPavo cristatus. 



Section of Entomology. October 25, 1871. 

 Mr. P. P. Mann in the chair. Thirteen persons present. 



Dr. H. A. Hagen read the following communication : — 



I wish to bring to your notice at this meeting a new kind of 

 pocket lens made by Carl Zeiss, of Jena, Germany, at a very low 

 price, and used and strongly recommended by Haeckel and other 

 naturalists. I have imported two sets, and examined three other sets 

 just imported by others. The definition of these lenses is perfectly 

 good and their great focal distance permits one to work very easily. 

 They are made on the plan of Bruck's lens, having a concave eye lens 

 adapted to the objectives. The following table shows their magnify- 

 ing power, focal distance and diameter of field, which is very large : 



Magnifying power. 



Focal distance. 



Diameter of field. 



8 diameters 



A\ inches 



.60 inches. 



18 " 



*A " 



.18 



« 



36 " 



i& " 







72 * 



i " 



.08 



« 



120) 



180 ; * 









f " 



.03 



<c 



