PROCEEDINGS OF THE SOCIETY. 
243 
The thanks of the Meeting were voted to Mr. Millett for his com- 
munication. 
The President read a paper descriptive of the Powell Iron Micro- 
scope, constructed by Hugh Powell in 1840, the instrument being 
exhibited in the room (see p. 209). 
Mr. Yezey said he was sure the Fellows would agree with him that 
their best thanks were due to the President for his very interesting 
description of the old instrument before them. It was essentially one 
of the functions of the Society to record the facts and development in the 
history of the Microscope, and in this special work no one had done 
more valuable service than the President. Mr. Yezey ventured to throw 
out a suggestion that if it were possible, an exhibition should be held of 
historic Microscopes, showing the various stages of the development of 
the instrument. He thought that, while all microscopists were ready to 
acknowledge the immense improvements which instrument-makers had 
introduced into the modern forms of Microscopes, yet it would be found, 
on examining the old instruments, that there were many valuable ideas 
which had probably been lost sight of. 
The vote of thanks was seconded by Mr. Michael, and carried 
unanimously. 
The President thanked the Fellows for the kind way in which they 
had passed this vote of thanks. He hoped the Society would see its 
way to arrange for an exhibition of old Microscopes which would not 
only be of great interest, but might also lead to the discovery of some 
points of value which had been hitherto overlooked. 
Mr. Julius Rheinberg read a paper in explanation of the chief fea- 
tures of the exhibition of multiple coloured illumination of objects 
arranged under about twenty-seven Microscopes in the room (see p. 142). 
The President said he was sure they would all highly appreciate 
Mr. Rheinberg’s kindness in giving them such an excellent demonstra- 
tion of his method of coloured illumination, which he had done at 
some considerable personal inconvenience. They would remember that 
Mr. Rheinberg first brought this subject to their notice in a paper read 
before the Society in 1896 (see Journal of that year, p. 373). In that 
paper all the various applications of his new method of illumination 
were fully dealt with, and it would therefore be unnecessary for him to 
go over that ground again ; therefore he did not propose to discuss the 
merits of this method in connection with the colour differentiation of 
structure in histological and other preparations, but he believed that 
one of the chief values of this new illumination was that it might make 
it possible to use a larger axial cone than heretofore. 
Sometimes cases arose where, from the tenuity of the object and other 
causes, they were compelled to use less than a 3/4 cone, and thus ran 
the risk of manufacturing spurious diffractive effects and other false 
images ; if then this new method made it possible to use the 3/4 cone 
in such cases, it would be a distinct gain. 
The Gifford screen had already accomplished much in this direction. 
