112 Scientific Intelligence. 
to work very well; and with a arrangement have had fine views of 
the test objects with the 4th and j5th in. “objectives, Some facts as to the 
structure of certain of the Diatoma, have been brought out with wonder- 
ful distinctness; there is a rotundity and solidity “which gives a more 
complete idea of the structure of such forms as Aulacodiseus Petersii, 
and the Amphiprore, than can be had by monocular vision. These ef- 
fects, however, are not to be had but by careful manipulation, and there 
microscopist would, however, succeed in bringing out very satisfactory 
effects with the means at present employe 
With the lower powers, 3 in. to $ds in. or yths in., nothing can exceed 
the beauty 0 — of oie seen for the first time with binocular 
vision. The transparent injections poset 1 by Smith, Beck & 
k are sonatas beautiful. Upon some of these I sonia the 
Wenham binocular and Mr. Tolles’s 6 piece. Tt i is with opaque objects 
bility in the eyes—the top and bottom of sonia thick preparations 
being seen together, or, at least, much better than when one eye alone 1s 
employed. At the same tim e, the Et sesieonit effect is wonderful : the 
field of view appears ealdeety: enlarged and comprehensive, and the mag- 
nifying power in te and the relief to the eyes is very great. 
The living Diatomacee and Desmidiz are shown with great effect with 
a good +4;ths or 1th sebectivy. They appear floating at different depths 
in a vast ocean, and with so little loss in definition that the cilie of Clos- 
terium Lunula are rea dily rved, as also those of the monads and 
larger animalcules, which appear like monsters in a vast dee eep. 
am not at liberty at present to explain the principle upon which Mr. 
Tolles has been enabled to divide the pencil so far from the objective; it 
is theoretically, as well as practically, —— and it appears a little 
strange that so obvious a principle did no once occur to those emi- 
nent Haro D See who _ dovctad ki so gears time and ek to the 
ments, ee the wn is hele in ene the same is and manner as 
the eye-piece. 
The use of the binocular eye-piece at once tests the quality of the ob- 
gd as none but —_ corrected glasses will give satisfaction; when 
wo in are formed by halves of the objective, and calling into 
especially the extreme portions, none but objectives of angle 
n 
