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objects; — will, no doubt, be duly appreciated by the scientific 
world. It will render every one capable of extending the 
powers of the microscope in a much greater degree than has 
hitherto been done; and thereby, must inevitably lead to 
the discovery of many of Nature’s minute secrets, which for 
want of such facilities have remained indefinite, or entirely 
concealed. The necessity of continually adjusting the micro- 
scope, from time to time, to follow the various movements of 
the animalculae, in rising to the surface, or descending into the 
depths of the fluid, is by this discovery rendered totally un- 
necessary. The evaporation of the fluid is very greatly dimin- 
ished by this invention; and, consequently, the examination of 
it, and of the various animalculae, &c. contained in it, may be 
prolonged to a much gieater period than could be effected 
under the usual modes of employing high magnifying powers. 
These great advantages may appear to many to be quite 
unattainable, by any thing less than a great expense in appa- 
ratus; but, when it is said, that the only addition to that 
usually employed, consists in laying upon the surface of the 
drop of fluid a thin slice of talc or mica, the wonder ceases; 
and we can only wonder that so exceedingly obvious, simple, 
and useful a contrivance shonld have remained so long un- 
employed. Of course, it will be understood, that the fluid 
should be laid upon the flat surface of a glass slip, when 
under examination. The animalculse in the water may be 
viewed under the power of a lens in a single microscope, of 
only one sixtieth of an inch focus, with the utmost facility; and 
also, the full powers of a compound microscope may be em- 
ployed in the same manner, the object lens nearly touching 
the talc. 
The substitntion of a slip of talc, in place of the two glass 
slips, usually employed in viewing transparent objects, well 
deserves to be universally adopted. This new application of 
it, however, to viewing the animalculae, &c. in flnids, will now 
render slips of 'talc an indispensible part of the microscopic 
apparatus: in their absence, one of the round talcs, usually to 
be met with, will be found highly useful upon many occasions. 
Instantly upon the talc touching the surface of the fluid, the 
capillary attraction between the talc and the slip of glass, 
disperses it on every side, and produces most of the beneficial 
