44 
PEOCEEDINGS OF SOCIETIES. 
dozen slides of fossil and recent diatoms. The specimens contri- 
buted by both these gentlemen were much admired for their skilful 
mounting. 
A hearty vote of thanks was returned to each of the donors. 
Encouraging letters were read from a number of practical working 
microscopists, expressive of the kindest hopes regarding the future of 
the young Society. 
A paper, contributed hy J. Edward Smith, of Ashtabula, Ohio, on 
the use of dammar varnish as a mounting medium for test objects, 
was read to the Society. Mr. Smith has found, from numerous expe- 
riments, that the varnish renders objects much more difficult of reso- 
lution than balsam. The increased transparency obtained by the use 
of the varnish seems to him to be the chief cause of the difference. 
The dammar mounts, according to Mr. Smith's experiments, utterly 
defeated a Tolles' immersion y-g th three system objective, which would 
readily resolve the same specimens when mounted in balsam. A 
Tolles' new four system y^th objective, however, readily resolved the 
dammar slides, though the same result could not be obtained by the 
use of any of the old objectives from y^th to -^oth. 
A paper was also read from G. W. Morehouse, of Wayland, New 
York, on the comparative results obtained by the use of Tolles' old 
three system, 5^0*^5 ^^^^ system, y^o-th. Mr. Morehouse 
states that the best work of the former was unequivocally excelled by 
the performance of the latter. This is a great gain, as the yo^^ gives 
a great increase of light and a better definition, as compared with the 
•^^oth. The most remarkable point in Mr. Morehouse's investigation 
is this : That the optician can, by a new and simple combination of 
lenses, with a focal distance as low as yoth of an inch, secure better 
performance than can be obtained by the old system, -^^th of an inch 
focal distance. This seems to be the greatest triumph of the optician's 
art, as regards the construction of objectives. 
A communication from J, Edward Smith fully corroborated the 
comparative statements of Mr. Morehouse. 
Mr. Dod, secretary of the Society, stated that he had ordered one 
of the new four system yV^^^j members could soon have 
an opportunity of judging from practical demonstration of the value 
of this new objective. 
The Board of Managers reported to the Society that they had 
purchased one of J. W. Queen and Co.'s students' microscopes, with 
accessions to the amount of one hundred and fifty dollars, in accord- 
ance with the expressed wish of the Society. 
The Society then adjourned, and the members proceeded to an 
examination of the slides lately received, and to a test of the perform- 
ance of a Gundlach's y^th objective on the Moller probe platte. This 
was followed by an interesting discussion of the theory of " ultimate 
atoms," as set forth by the president. Dr. Cutler. 
