212 PROCEEDINGS OF SOCIETIES. 
notice, such as the wheel-shaped spicula of Chirodota figured by 
Dr. Carpenter in his work on the microscope; also a section of 
agate, brought by Dr. Murie from the Nubian desert, consisting 
of an aggregation of regular formed crystals, beautifully shown 
by polarized light; likewise a mineral called sunstone, as an 
opaque object rivalling in iridescence and colour the elytron of 
the diamond beetle; also spicula of a synapta more than four 
times the size of those generally met with. 
Messrs. PowEtt and Lrananp.—Seven of their splendid first- 
class instruments, and the following objects :— Circulation of the 
valisneria (with their new z4th objective), Volvor globator, peri- 
stoma of moss, gastric teeth of cricket, leaf insect, circulation in 
young of trout, and tail of fish, &., &e. 
Mr. Ross.—A magnificent display of twenty-four of his first- 
class instruments. Although the objects presented no novelty, 
the brilliant illumination and definition were very remarkable, 
We particularly noticed a slide of “ Heliopelta,’ mounted as an 
opaque object, shown in a binocular with the 3-inch of 90°, and 
its Lieberkuhn. 
Messrs. Smrru and Brecx.—Twenty-four microscopes; also 
two instruments connected with the early history of the com- 
pound achromatic microscope. 
The one was a microscope stand, designed by Mr. Lister in 
March, 1826. The work was executed by James Smith, under 
Mr. Lister’s superintendence, and was finished in 1827. This 
instrument is the basis from which has been built up all the 
improvements in the achromatic microscope which have taken place 
inthiscountry. The object-glass was worked by Mr. Lister’s own 
hands in 1880, and its aperture was at that time larger than any 
other glass made either before or for some time after. 
The other was the first complete microscope made by James 
Smith on his own account. It was ordered by the late Mr. R. 
L. Beck, and delivered to him May 29th, 1839. 
In connection with microscopic objects, the same firm also ex- 
hibited the “life history’ of an acarus, identical in appearance 
with the Acarus Crossii. The various stages from the egg to the 
mature male and female were separately shown, in a living state, 
by six instruments, accompanied with drawings at the side of each. 
The construction of these microscope stands, intended for purposes 
of demonstration, was entirely novel, and besides being of very 
moderate cost, the arrangements entirely prevented any inter- 
ference with the object—a precaution which so many find to be 
necessary on such occasions. 
In one of their ordinary best microscopes a Podura scale was 
shown, under a 2,th. This particular specimen exhibited in a 
striking manner the continuity of, the markings—a subject which 
was still further illustrated by drawings of the scales from five 
different species, magnified 1300 linear. Under some of their other 
microscopes Smith, Beck, and Beck also showed some entirely 
new and exceedingly fine carmine injections. 
