88 BROOKES, ON MICROSCOPES AT THE EXHIBITION. 
processes concerned in the growth and development of the various 
tissues of which animal frame is composed. Some preparations 
are also exhibited illustrating the preservative effect of a weak 
aqueous solution of wood-naphtha and creasote. 
J. H. Datimeyrr, M. (United Kingdom, 2888), exhibits 
microscopes constructed after the model of his late father-in-law, 
Mr. A. Ross, whose talents were long so successfully directed to 
the improvement of the microscope. These are, as might be 
expected, first-class instruments; but in their construction, Mr, 
Dallmeyer’s artistic power has not experienced as successful a 
development as in his astronomical telescopes previously men- 
tioned. 
J.B. Dancer, Manchester, M. (United Kingdom, 2889), exhibits 
a patented form of binocular microscope, in which the two pencils 
pass symmetrically through an achromatized double prism, As 
previously stated, it is very questionable whether any contrivance 
for the symmetrical divergence of the pencils by means of refract- 
ing prisms is desirable. In this the light is a good deal reduced 
by the narrowness of the rectangular aperture through which the 
pencil is transmitted. Mr. Dancer’s reputation for the successful 
production of microscopic photographs is well known, and fully 
sustained by those exhibited. A group of four well-defined por- 
traits of eminent persons is so small that the width of each con- 
taining oval is one fiftieth of an inch. 
P. Fritru & Co., Sheffield (United Kingdom, 2899), exhibit 
some well-made microscopes, at moderate prices, for the amount 
of workmanship expended on them. Their optical properties are, 
however, hardly equivalent to the soundness of their mechanical 
construction. 
S. Hieutry, M. (United Kingdom, 2912), exhibits some very 
commendable forms of microscope for students and general use, 
at a very moderate price. Among these are the late lamented 
Professor Quekett’s dissecting microscope, neatly packed wp as a 
pocket companion; and Professor Beale’s admirable instrument 
for the lecture-room, at the moderate price of £3 3s. 
Horxe & Toorytuwaire, M. (United Kingdom, 2916), exhibit 
a full-sized and well-finished microscope, the only noticeable 
peculiarity of which is that there is a small amount of tilting or 
rocking motion communicable to the stage, by means of which an 
object, not mounted parallel to the surface of the slide, may be 
brought to coincide with the plane of vision. They exhibit also 
an aplanatic eye-piece; this is not really so great a desideratum 
as might be supposed, inasmuch as the best-constructed objec- 
tives are usually a little over-corrected, to compensate for the 
chromatic aberration of the ordinary Huyghenian eye-piece. 
W. Lapp, M. (United Kingdom, 2925), exhibits microscopes of 
considerable merit. The instruments of Mr. Ladd have been 
long and favorably known to microscopists for the substitution 
of a chain-movement for the ordinary rack and pinion, whereby 
great smoothness of motion is attained, together with the entire 
