38 J. P Cooke—Buoyancy of the Atmosphere. 
which were cracked and fissured were seen. Near the fissures 
quartz showed evident signs of having been exposed to ine 
terial. 
The sections show not the slightest trace of characters belong- 
ing to any meteorite that has yet been examined microscopically 
either by myself or by others, so far as can be ascertained by 
their published descriptions. Tt is apparently a slag and most 
probably derived from the earthern- -ware manufactory at some 
earlier date. 
No blame attaches to Mr. Crosby, for ee undoubtedly acted 
to the best of his knowledge in making his observations and 
statements ; and it will be notes that bis remark, that it lay 
upon the surface while the grass was untouched, was opposed 
to its mers origin and in accord with the results of m 
examinatio 
Cambridge, a. April 14th, 1883. 
ArT. VI.—A Simpie Method of Correcting the see le of a Body 
for the Buoyancy of the Atmosphere when the Volume is un- 
known; by JostaH Parsons COOKE. (Conti bateans from 
the Chemical Laboratory of Harvard College.) 
Ir is a familiar fact that in the usual method of accurate 
weighing the buoyancy of the atmosphere produces a sensible 
effect whenever the volume of - load differs materially from 
that of the equipoise. But, as in all ordinary processes of 
chemical analysis the analyst deals solely with relative weights, 
the presence : a perfectly dry atmosphere does not influence 
his results, unless the conditions of temperature and pressure 
have changed between the successive weighings: and even then 
the ge is insignificant in most cases. Still when the volume 
the sont of the air under the standard ccnalieaiie as well as 
the temperature and pressure at the moment of the ‘several ob- 
