32 
Instead of placing the mirror immediately over the opening 
at the back of the object glass, a small speculum J of an 
inch in diameter is introduced into the front of the body of 
the microscope, 2^ inches above the top of the objective. 
A lateral opening is made in the body at right angles to the 
speculum, for the admission of light to be reflected down 
through the objective to the object below. 
The interposition of the small speculum does not produce 
any disagreeable effect in the field of view, and in the exami- 
nation of objects it is easy to use that portion of the field which 
is between the centre and the edge. With proper manipulation 
very good definition can be obtained by this method, when 
the speculum is of the proper curvature. This contrivance 
can always remain attached to the microscope without inter- 
fering with the general appearance of the instrument, and 
when the use of the speculum is not required, it can be with- 
drawn or turned aside out of the field of view, and the aper- 
ture at the side of the body may be closed by a small shutter.* 
It is obvious that the use of the binocular body is not inter- 
fered with by this arrangement. 
A binocular and a monocular microscope with this arrange- 
ment were exhibited to the members at the close of the 
meeting. 
* 
Mr. Hardy (on behalf of Edward Ross, Esq.) exhibited a 
large cetacean vertebra which had been found in the valley 
of the Don, about two miles from Tinsley and four from 
Rotherham, in Yorkshire, on a line of railway now in course 
of construction. The bone was met with in excavating, at 
a depth of 14 feet below the surface of the ground, in a bed of 
gravel overlaid by the alluvium of the valley. In answer to 
questions put by Messrs. Binney and Hull, Mr. Hardy 
described the bone as one of the lumhar vertebrae of a species 
of whale, probably identical in genus with* the balaena of the 
present seas. The bone measured on its largest diameter a 
