1894.] MICROSCOPICAL JOURNAL 183 



fundamental properties of lenses and systems of lenses, and the 

 theory of spherical aberration. Chapter five is on the theory of 

 achromatism and chromatic aberration. Chapter six is on 

 prisms and system of prisms ; seven is on stops and aperture 

 and properties of an optical system, which depends upon aper- 

 ture, such as penetrating power and brightness ; nine is ujion 

 the principal types of optical instruments, and ten treats of the 

 methods for determining the constants of optical instruments. 

 Much of the data is new to science and a distinct advance in 

 physical research. The account of Abbe's theory of micros- 

 copical vision is not published, but withheld for a separate 

 volume. 



The Beaver Creek Meteorite.— It fell May 26, 1893 about 

 4 o'clock a. m., at Beaver Creek, West Kootenai District, B. C. 

 It is of gray color and granular structure. In thin sections 

 under the microscrope Merrill states that it presents no features 

 not common to such stones. Structures are recognized similar 

 to the meteorites of Madras, Homestead, Dhurmsala and San 

 Emigdio. He says : " There are the usual monosomatic and 

 polysomatic chondri sometimes of olivine alone, enstatite alone, 

 or olivine and enstatite together, in granular or porphyritic 

 forms with glassy base or radiating and barred forms. The 

 olivines not infrequently occur with interiors made up of small 

 rounded granules imbedded in a glass base, but extinguishing 

 simultaneous with the outer portion." 



A chemical analysis will be found in the American Journal of 

 Science for June. 



MICROSCOPICAL APPARATUS. 



King's Glycerine Jelly.— Dr. King sends us the following 

 regarding his improved formula. Glycerine Jelly is the best 

 mounting medium where shrinkage is to be avoided, protoplasm 

 preserved, and the finest differentiation of details to be attained. 

 The objections to its use arise more than anything else from a 

 lack of patience to overcome some slight difficulties in manipu- 

 lation. 



This Glycerine Jelly is made with an expensive gelatin from 

 the swimming bladder of the sturgeon, a very different thing 



