223 Ro7jnl Socieiy:. 



derably above that of water, while the lowest dispersive 

 power is very much below that of water. 



February 25. In consequence of the continued indis« 

 position of the President, the Earl of Morton, Vice-presi- 

 dent, was in the chair, when a paper by Dr. Wollaston was 

 read, containing a description of his newly invented single 

 lens micrometer. This instrument is made like a common 

 telescope, but the focus of the lens is only l-12th of an 

 inch : this glass is placed behind a brass plate, through the 

 centre of which an eye-hole is drilled j the subjects to be 

 viewed are placed between glasses serving as object glasses, 

 and the measure of the magnifying powers and of the sub- 

 jects examined is taken by means of a certain number of 

 wires fixed near the object glasses. The measure and num- 

 ber of the wires being determined, the objects may be ex- 

 tended to such distances as to give their dimensions by 

 making a wire the two hundredth part of an inch cover 

 them. The description was illustrated by designs of the 

 micrbmeter, which the author adopted in consequence of 

 his experiments on drawing very fine wires, some of which 

 did not exceed the thirty thousandth part of an inch ; but 

 they were incapable of supporting themselves at this fine- 

 ness, and were broken in very short pieces. He found wires 

 .18000 of which covered an inch, to be the finest and 

 strongest for any useful purpose. 



A paper by Dr. Pearson, on the tingeing rnatter of 

 the bronchial glands of the lungs, and on the blaclt 

 or tingeing matter of the lungs themselves, was read. 

 From his researches it appears that this black matter is 

 principally charcoal in an uncombined state, or at least 

 that it is only intimately mixed with a small portion of 

 anrmal matter. He conceives that it is derived from the 

 atmosphere in breathing ; that it is first conveyed into the 

 air-tubes, and from thcni by means of the numerous lym- 

 phatics into the bronchial glands, and therefore that it is 

 not a secreted substance. 'I his subject being so novel. Dr. 

 Pearson declined entering into much reasoning or drawing 

 many conclusions until more facts are brought to light. 



March 4. Eail Morion in the chair. A letter from the 

 late Mr. W. Kiiby Trimmer to the Kight Hon. Sir Joseph 

 Banks was read. It gave a description of the fossil re- 

 mains found in two fields near Brentford, Middlesex, in 

 digging brick earth there. In the space of 120 square 

 yards, nine teeth of the hippopotamus were found ; also 

 elephants' tusks nine feet long, deer's horns and teeth, river 

 ^nd marine shells, fish bones aud teeth, Sec, in great num-- 



bers. 



