324 
PROCEEDINGS OF SOCIETIES. 
on an object, below which is placed an illuminated circular disk at a 
distance of ten times its diameter. The power is in the inverse pro- 
portion of the diameter of the disk to its diminished image in the 
eye-piece. 
Example. 
Diameter of disk -25 
Distance from focus 2*5 
Diameter of diminished image .. .. -0182 
1 -i- -0182 =: 54-94 
The power required. 
A slit or divided scale may be substituted for the disk, provided that 
it be placed at a distance of ten times its unit of length from the focus. 
The disk or scale can be measured by a double-image dynameter, 
or by a microscope with a Jackson or other micrometer. 
Dr. Lawson : Human cerebellum and spinal cord of cod. 
Mr. Lettsom : Professor Noerremberg's wide - field polarizing 
microscope, and Brookite, chrysoberyl, corundum var. ruby, parisite, 
platinocyanide of yttrium, Smithsonite, and titanite. 
Mr. Moginie : Diatoms from Eichmond, U.S. (Systephania). 
Mr. Mclntire : Curious butterfly scales, species ? 
Dr. Millar : Sections of new sponges, Dactylocalyx poly discus and 
Acantliospongia Smithii. 
Mr. Norman : Crystals of gold and sporules of fungi. 
Mr. Palmer : New micro-spectroscope apparatus for measuring the 
position of bands, with illustrative specimens including solution of 
pyrethrum in ether. 
Mr. Walter W. Peeves : Fructification of Chara, Chara foetida, 
with globules containing the spiral filaments ; and Chara fragilis ? 
with the spiral filaments squeezed out of the globules. 
Mr. James Smith : Elytron of beetle, Chrysolophulus speciahilis. 
Mr. H. J. Slack : " Brighton pebble," with red round hollow 
bodies, perhaps fossil (?). 
Mr. J. H. Steward : Fire-tailed bee. 
Mr. Sigs worth : Ovaries of various plants, with ovules ^w situ. 
Mr. Charles Stewart : Pedicellaria of one of the echinoderms. 
Mr. H. C. Sorby : Eed clay and other deposits from great depths 
in the Pacific Ocean, from the ' Challenger ' expedition. Various 
sjjecimens show that the red clay contains grains of sand as well as 
volcanic products, and is in many respects analogous to the gault and 
other fine-grained deposits. Also various colouring matters derived 
from bile occurring in vomit, with other specimens illustrating their 
nature and their connection with those found in normal feces and 
urine. The part soluble in ether gives a spectrum quite unlike that 
of the analogous substance from the bile of the ox or sheep. That 
soluble in water contains the same colouring matter as that found in 
normal feces, and another apparently identical with a product obtained 
by the oxidization of the bile pigment present in the urine of certain 
cases of jaundice, and analogous to a constituent giving a well-marked 
spectrum, present in variable quantity in normal urine. 
Mr. Topping : Section of the head of lamprey. 
