PROCEEDINGS OF SOCIETIES. 
327 
one at each corner, these, when weighted, become extended, and thus 
shift their points of contact with the support, producing friction, 
which tends rather to promote vibration than to absorb it ; but if 
these springs be made to rest upon and be attached to four other 
similar springs in an inverted position, any upward tremor commu- 
nicated to the lower set will be taken up and destroyed by the upper 
set, and so leave the top board comparatively at rest. In the instru- 
ment described india-rubber rings were employed, the compression of 
one set of rings being counterbalanced by another set extended over 
the corners, which were notched out to receive them : other springs 
being inserted at intermediate points to secure greater stiffness of 
action against lateral movement. The two boards being thus in 
contact only through the medium of the rings all upward tremor from 
passing traffic was effectually destroyed, and the microscope and lamp 
being supported by the turn-tray could be readily passed from one 
observer to another without any alteration of position. 
Ordinary Meeting, October 27, 1876.— Henry Lee, Esq., F.L.S., 
President, in the chair. 
Mr. T. C. White read a paper upon the Fly Fungus, Emjpiisa 
musci, in which he detailed its appearance and peculiarities, illus- 
trating the subject by specimens exhibited under the microscope. 
Mr. W. K. Bridgman read a paper " On a New Universal Keflecting 
Condenser." The design of this arrangement was to acquire a control 
over the angle of illumination, so as to be able to direct the light 
readily at any degree of obliquity from a dark ground to axial rays, 
and thus not only to secure the proper angle for every object and any 
objective, however wide-angled, but also to be applicable to all other 
purposes. A small metal speculum was fixed vertically to a cross- 
bar, which also carried a second reflector acting as a stop or dia- 
phragm, and opened and shut by a screw so as to regulate the 
quantity of light admitted. The light thus passing through a narrow 
slit, and being reduced almost to the same plane, was deprived of all 
cross rays tending to interfere with distinct vision, and as the reflector 
and its stop could be moved backwards and forwards, and also inclined 
at any angle by a simple finger and thumb movement, it admitted of 
being adjusted with the greatest nicety. By these means the angle of 
illumination could be gradually changed until the most suitable effect 
was produced — a certain obliquity causing light to be reflected down 
upon the object from the covering glass, giving the effect of surface 
illumination in addition to transparency, and bringing out surface 
markings in a manner not otherwise so easily attainable. 
Mr. W. H. Gilburt read a paper " On the Eolations of Volvox 
globator to Sphoerosira volvox" showing that the last-named form, 
which had been classed as a distinct species by Ehrenberg, was, as 
had been suggested by Mr. Busk and others, only a stage in the life 
history of the better-known V. glohator. The writer had found a 
large number of V. globator, containing one or more Sphoerosira, 
together with other macro-gonidia, it being a very rare exception to 
find more than one. He also described the compound discoid bodies 
found in Sphoerosira, and certain differences observed in the other 
