LoBB, on Illuminating Objects with High Powers, 39 
The illumination of the whole fields or the throwing of the 
light more or less on one side, can easily be accomplished by 
the use of a small condensing lens placed about the distance 
of its own focus from the lamp_, and slight alterations in its 
position will, so far as I have tried, produce quite as good 
results as any diaphragm with small apertures at the side, 
I feel confident that this method of illumination will prove 
a valuable addition to the microscope. It is a subject of 
great importance and interest ; but it requires, so far as we 
know at present, careful and thorough investigation. 
Note on Illuminating Objects with High Powers, 
By E, G. LoBB, Esq. 
(Read January 10th, 1866.) 
There are several methods of illuminating with high 
powers. The late Professor Quekett, in his treatise on the 
microscope, recommends oblique light with the mirror and 
lamp, removing all appliances under the stage; then after 
much patience and perseverance Grammatophora subtilissima 
and the Amician test may be resolved. 
Another plan is to use the flat mirror, the achromatic con- 
denser and a paraffin lamp, daylight not being so easily 
managed, or even so good for the ^th or higher objectives. 
Some use the mirror and a prism, so placed that the light 
may be thrown on the object at right angles. Others use 
two prisms and two lamps for the same purpose. Others use 
the Rev. J. B. Readers kettle-drum. In fact, multifarious 
are the methods adopted by different parties^ and very suc- 
cessful have been the results obtained. 
My own method is as follows, which does for all descrip- 
tions of objects, whether lined or not : — 
The microscope is placed in the horizontal direction, and a 
small camphine lamp so adjusted that its reservoir may be 
close against the end of the rack-tube ; having the A eye- 
piece, the one-inch objective, and the achromatic condenser 
of 170^ aperture, place No. 1 aperture of the wheel of dia- 
phragms in the field, then, looking through the eye-piece, 
centralize the aperture; this done, put No. 11 aperture in 
the field, then centralize the lamp flame; everything will 
now be in the axis of the pupil of the eye. 
Should it be wished to examine hairs, scales, or morbid 
structure, use No. 3, 4, or 5 apertures of the wheel of dia- 
