PROCEEDINGS OF SOCIETIES. 
275 
front of the lens. Of the two positions, it would be far more beneficial 
when placed in contact with the object. 
Dr. Pigott thought that one other point was important — he be- 
lieved it was stated that the measurement extended to the o-^wooo iiich. 
The President said that the scale was divided, so that the tables 
enabled the reading to be made of millionths of millimeters, and the 
decimals would be ten millionths. His own impression was, however, 
that they could not be certain of anything less than the millionth of 
a millimeter. 
A paper " On the Microscopical Structure of Amber," by Mr. 
H. C. Sorby and Mr. P. J. Butler, was read by the President, who 
illustrated the subject by numerous drawings enlarged upon the black- 
board. (The paper will be found printed at p. 225.) 
Dr. Pigott said, with regard to the included globules, he was 
engaged some time since in examining the refractive index of glo- 
bules, and he found that the stronger the refractive index, the smaller 
was the central spot seen. There was a very beautiful mathe- 
matical relation between the nuclei shown by water, or gas, or other 
fluids. 
The President said he much regretted the absence of Mr. Butler 
that evening, because it was to him that the merit of the paper was 
chiefly due for the greart number of sections which he had prepared, 
and the amount of time which he had devoted to them. 
A vote of thanks to Mr. Sorby and Mr. Butler was put to the 
meeting by Mr. H. J. Slack, and carried unanimously. 
The Secretary said they had received a paper from Dr. William 
Hinds, of Birmingham, " On a Curious Fact in connection with 
certain Cells in the Leaves of Hypericum androscemum," but owing 
to the lateness of the hour it would not be possible then to read it. 
The contents of the paper were stated, which was " taken as read." 
(See p. 233.) He also reminded the Fellows that they had received 
some time ago a quantity of specimens of minerals and diatomaceous 
earth from Mr. Hanks, of San Francisco, and that the earth had 
been sent to Mr. Kitten for examination. That gentleman's report 
would be published in the Journal (see p. 232), and he thought 
would prove interesting, as tending to reduce the number of species 
of Aulacodiscus, &c., by showing that the furrow had little value as a 
specific character. He had written to Mr. Hanks for a further supply 
of this earth, and if it existed in large quantities, and it were possible 
to send them several pounds weight of it, an examination of so large a 
quantity would probably result in a still further reduction. 
The Secretary called attention to a section of a so- called " Brighton 
pebble," exhibited under a microscope in the room, and containing 
small objects, resembling those figured by Dr. Duncan in the May 
number of the ' Quarterly Journal of the Geological Society.' 
It was also provisionally announced that, subject to permission 
being obtained for the use of the rooms, a scientific evening would be 
arranged by the Council for the second Wednesday in November.* 
* The permission was subsequently obtained. 
