WaringtoNj 071 Additions to his Microscope. 59 
yielding faithful and accurate results from the class of objects 
submitted to its powers. 
In using the microscope for the aquarium several difficul- 
ties present themselves : Firsts the want of lights though this 
may, to a certain extent, be supplied by concentrating the 
sun's rays or the light of a gas or oil lamp, through the 
medium of reflectors or condensing lenses, upon the object 
to be examined ; secondly, the necessity there is of bringing 
the subject under investigation within the focal distance of 
the objective lens, obliging generally the removal of it from 
its naturalised position in the tank ; and thirdly, the great 
thickness of the glass, with which the tanks are necessarily 
constructed, preventing the employment of any other lenses 
than those of very small magnifying power. To get over 
these several difficulties I have adopted numerous con- 
trivances, all of which, to a certain extent, answer the par- 
ticular purpose required very well, and which I shall now 
proceed to describe. 
The first adaptation consists in the employment of stone- 
ware pans as rock-pools, the sides of which rise at right 
angles to the- base, and are constructed of such a thickness as 
to allow the small clamp of the portable microscope to be 
fastened on its margin at any part, the bearing surfaces of 
the clamp being faced with discs of cork or vulcanized india 
rubber, in order to prevent the fracture of the sides of the 
pan from any uneven pressure by the leverage of the screw. 
The next is to attach the microscope to an upright squared 
rod of well-seasoned wood, inserted into a heavy foot, capable 
of sustaining the weight of the instrument when in use, as 
shown at fig. 1 ; the rod being of such thickness as to admit 
of its being readily embraced by the jambs of the clamp. 
With this arrangement it will be evident that the operator 
can readily elevate the microscope to any height he may 
require, while the elongation of the rod, in the horizontal 
direction, enables him to project it over the surface of the 
water in the aquarium. A contrivance, somewhat analogous 
to this, has, since my employment of it, been proposed by 
Dr. Redfern, and was described by him at the meeting of the 
British Association in Dublin, in 1857, and was afterwards 
published in the ' Quarterly Journal' of the Society, vol. vi, 
p. 77 ; but I believe my own arrangement will be found more 
simple, equally efficacious, and much less expensive. 
The third contrivance consists essentially of two parts, the 
first of which is to establish a sort of magnified live box, so 
enlarged as to admit of growing vegetation being introduced 
into its interior, and by this means, and with the proper 
