16 fi 
PROCEEDINGS OF THE SOCIETY. 
Mr. E. M. Nelson read a brief obituary notice of the late Mr. 
William Tarn, whose death at a comparatively early age had recently 
occurred. Being a silent member, it was not generally known that, 
owing to his knowledge of science and his skill in manipulation, 
microscopy had sustained a distinct loss. 
Mr. T. H. Powell said he could thoroughly endorse all that Mr. 
Nelson had said as to the abilities of Mr. Tarn. 
Mr. Nelson said that when calling attention to a drawing at the 
last meeting as being made with an apochromatic giving a magnifying 
power of x 850, he had omitted to say that the objective used was one 
of 1/12 in. by Powell, which had proved to be a remarkably fine 
glass, free from colour and showing a great speed in photography. It 
was furnished with a correction collar, and had also the further merit 
of being the cheapest apochromatic yet produced. 
Mr. H. Bernard exhibited and described a new form of mechanical 
stage for use with the Microscope, specially designed to obviate the 
inconvenience so frequently arising on account of the very limited range 
of motion admitted by those at present in common use. Kegarding 
the fingers as the best means of movement, he had endeavoured to 
imitate their action, and had put the mechanical arrangement by which 
it was effected under the stage. He had shown the drawings to Prof. 
Abbe, who said he thought the idea was the best of the kind he had 
yet seen. The one which he had brought for exhibition that evening 
had been made from these drawings, and though not yet perfect in all 
its details, it was sufficiently so to render the principle of construction 
perfectly clear to any one who inspected it. It would be seen that the 
movement obtained across the stage was as much as 10 cm., and in the 
other direction it was 5 cm., which was not only larger than what was 
obtained in any other form, but it would carry the largest slip likely 
to be required, and would show it from end to end. It was also of 
great use for the purpose of observing living objects, as it would take 
a zoophyte trough, and not only keep it in position, but enable it to 
be moved from end to end without shaking or disturbing the contents ; 
and it would also equally well carry a watch-glass with liquid in it, or 
a pair of light forceps for holding solid objects. 
The President, in thanking Mr. Bernard for bringing this stage to 
their notice, expressed the opinion that it was likely to be found very 
useful for dissecting, during which he had often felt the inconvenience 
arising from the -want of a greater range of movement in the ordinary 
mechanical stage. 
Prof. Groves read a letter received from Mr. M. J. Hermann, de- 
scribing the position of a pond in the neighbourhood of Balham, which 
he had recently found to contain Volvox globator in unusually large 
quantity. A sketch map indicating the exact locality accompanied the 
letter and was copied upon the blackboard. 
