BROOKES, ON MICROSCOPES AT THE EXHIBITION. 89 
absence of “loss of time.’’ This is applied both to the coarse 
adjustment, for raising or lowering the body of the instrument, 
and to the rectangular movements of the stage. The adjustment 
of the secondary stage is of a very simple and effective kind; the 
stage consists of three brass plates superposed on each other, the 
lower one being attached to the body of the instrument, and the 
upper one to the tube which carries the illuminator. The middle 
plate is connected with the external ones by two pins distant 90 
from each other, and each moved upon the other by a rack and 
pinion. Mr. Ladd has also a very neatly arranged magnetic stage. 
‘Two small magnetic bars are inserted in the stage-plate, and a 
gilt iron bar placed across these adheres in any position in which 
it is placed, and supports the object. The quality of the objec- 
tives is good, but not first-rate. The lightness and portability of 
the stand have already been alluded to. 
J. Parkes & Son, Birmingham, H. M. (United Kingdom, 
2943), emphatically state that their aim has been to produce con- 
venient, well-proportioned instruments, at the lowest possible price, 
and no doubt this object has been successfully carried out, as 
their simplest forms of compound microscopes are extremely cheap, 
the lowest cost being only 10s. 6d.; these may be the means of 
introducing a healthy and inyiting pursuit amongst large classes 
to whom more eflicient instruments would be obviously unattain- 
able. This firm has boldly attempted to develop a new point of 
union between art and science, in the production of a large 
“Fine Art” microscope. As taste,is ‘proverbially not amenable 
to any known law, it is hoped that this “work of art” may not 
remain unappreciated; but an irresistible conviction arises that 
the body of a microscope mounted on the back of a dolphin, or a 
griffin, or anything of that sort,is an incongruous and uncom- 
mendable monstrosity. 
M. Pruxiscurr, M. (United Kingdom, 2945), exhibits a con- 
siderable variety of microscopes, some of which may fairly claim 
the denomination of first-class instruments; and the advance of 
his recent exhibit from that of 1851 evinces much persevering 
industry. His brass-work is very good; it is generally on the 
“ Ross”? model, except that a little curvature is given to the out- 
line of the vertical supports. The optical work is good, but has 
not yet reached the highest standard of excellence. The object 
in his collection which was considered most entitled to commen- 
dation, was a very compact student’s microscope in a neat ma- 
hogany case. The objective consisted in a triple achromatic com- 
bination ; the first, composed of three lenses, made a good objec- 
tive of one-inch focus. The addition of the second, a correcting 
combination of two lenses, gave an indifferent half-inch objective ; 
but the addition of the third combination constituted a very 
effective glass of quarter-inch focus; and the price of the whole, 
namely £5, does not exceed that of a quarter-inch objective alone, 
by either of the first makers. 
Powztt & Luanann, M. (United Kingdom, 2946). The exhibit 
