1893.] MICROSCOPICAL JOURNAL. 301 



at the lOth International Medical Congress at Berlin in 1S90, 

 displayed a considerable number of photos, proposes to do the 

 same at a lecture before the Royal Imperial Society of Physi- 

 cians in Vienna, illustrating the advantages of photography for 

 scientific purposes. In order to be U]? with the times, the un- 

 dersigned most respectfull}^ asks if you cannot send hini as soon 

 as possible, a few of your be?t photos ? " 



Chicago : 1892. — Seeing in the notices of the \¥orld's Fair 

 that special agents, sent for the purpose, had secured the most 

 powerful microscope in the world to be brought from Europe, 

 I was anxious to know whether it excelled the American ]-75th^ 

 I wrote to Dr. Peabody the Superintendent of the Department 

 of Arts and Sciences that I could not find a practically useful 

 higher power than the l-75th, but that after this announcement 

 there ought to be and that if Europe was given the first place in 

 the procession when it belonged to America he would stir pa- 

 triotism in such a way that he would be likely to hear from it. 

 The gentleman kindly replied through others, that there was 

 no objective beyond the l-75th. and invited me to exhibit it. 

 Things beyond control prevented. There is more evidence, but 

 the above is ample to sustain the claim that America has pro- 

 duced the best highest power objective, which has stood the 

 test for twenty years. 



Illumination of this Objective. — Mr. Tolles made a spe- 

 cial substage condenser. Privileged to look through this objec- 

 tive at human blood, I thought that the field was darker than 

 it ought to be, from the loss of light by reflection from the mir- 

 ror, and from the smallness of the condenser lenses. I had prac- 

 tically found that direct light as used more than 200 years ago 

 was more than ample for ordinary work, especially if the thin 

 edge of the oil flame was employed with a Huygen's eyepiece, 

 which wonderfully condenses radiant light to a focus, about a 

 half inch from the face of the eyepiece, the larger lens being to- 

 ward the light. I asked tlie privilege to put these ideas into 

 practice. It was given. All substage apparatus was removed, 

 save the diaphragm holder, to which the B eyepiece was fitted 

 with a roll of paste board. The eye glass with cap removed, 

 was toward the stage. The field glass was turned towards the 

 thin edge of the flame. 



The tube of the microscope was aimed at the flame which was 



