PROCEEDINGS OF THE SOCIETY. 
543 
several weeks Dr. Czapski replied that he had not found any trace of a 
“ chemical ” focus non-coincident with the visual focus, and the objective 
was again forwarded to London. The committee then met, and the same 
fractured valve of P. angulatum was focused accurately and theu 
photographed, and it appeared quite sharp in the photograph. The 
transit of the objective from London to Jena had somehow got rid of the 
“ chemical ” focus. Unfortunately, as he had already stated, the slide 
had become seriously deteriorated, so that the critical tests which they 
intended to photograph could no longer be tried. They were therefore 
compelled to wait the arrival of another slide, which Dr. Van Heurck 
had most kindly sent ; but which the committee had not yet been able 
to examine. He trusted the matter would be dealt with satisfactorily 
during the recess, though he must express his regret that the trials 
would necessarily be limited to the one slide, the diatoms on which had 
undergone very rough treatment in being imbedded in the surface of the 
flint glass by melting, and by the addition of the dense mounting medium, 
which, according to Dr. Van Heurck’s statement, required a temperature 
of 400-500° Centigrade for its preparation whilst actually on the slide. 
Mr. Andrew Pringle’s letter was read, in which he expressed his 
regret at not being able to attend the meeting to describe the new 
photomicrographic apparatus recently made to his instructions, by 
Messrs. Swift and Son, for the Royal Veterinary College. 
Mr. Mayall said Mr. Pringle’s letter had reached him only a few 
minutes before the Council meeting ; but as he had had an opportunity 
of examining the apparatus before it was brought to the Society, he 
would endeavour to call attention to the principal points. From the 
very early days of photography the Society had been kept well informed 
of the progress of photomicrography, and had from time to time received 
a great number of photographs representing the progress made. They 
had also received many communications describing the apparatus and 
methods employed. The most notable, from every point of view, were 
the photomicrographs produced by the late Dr. J. J. Woodward, of 
Washington, who had been most careful and exact in describing his 
methods and in figuring the installation of his apparatus, which was, 
without doubt, the most perfect of its date. In Dr. Woodward’s work 
every branch of microscopy extant in his time had been dealt with, so 
that his successors were bound to rate their progress by comparison 
with his work, which was, however, wholly produced before the days of 
the modern “ dry-plate ” processes of photography. The simplification of 
the manipulations due to the dry-plate photography had greatly 
popularized photomicrography, so that nearly every microscopist who 
had tried his hand at producing a few photographs, considered himself 
justified in devising some special form of apparatus, as evidenced by the 
enormous mass of appliances that had been figured and described in the 
Society’s Journal. 
Hitherto it might be said that the inventors had generally limited 
their efforts to the application of some form of camera to an existing 
type of Microscope, the latter being the particular instrument with 
which they were most familiar. Even Dr. Woodward, who had practi- 
cally unlimited means at his disposal, contente 1 himself with combining 
his favourite Microscope (Powell and Lealand’s No. 1 model) with a 
