240 H. L. Smith on a new Illuminator for Opaque objects. 
stated. It would be strange if the idea of a reflector behind 
the objective had not oceurred to this ingenious and veteran mi- 
croscopist; but if so he seems never to have carried it out in 
practice. In the annual address of the President of the Micro- 
scopical Society of London, Feb. 11, 1857, four years after he 
proposed the annular ring, we find the following: ‘This is a 
problem,” the illumination of opaque objects under the highest 
powers of the microscope, ‘the solution of which has been at- 
tempted by numerous adepts in manipulation with only very 
pe success,” m’ 
diaphragm, 
nearly as far as it will go. Turn the reflector on the axis of the 
light, will quickly accomplish 
Ps ad for focus; if the field 8 
