99 
Ordinary Meeting, February 20th, 1872. 
E. W. Binney, F.R.S., F.G.S., President, in the Chair. 
The President said that at the meeting of the Society 
on the 9th of January last he alluded to the probability of 
the genus Zygopteris being found in the limestone nodules 
of the Foot Mine near Oldham. He had lately had an 
opportunity of inspecting the collection of Mr. James 
Whitaker of Watershedding, and he there recognised a 
specimen of the Zygopteris Lacattii of M. Regnalt. There 
■was a difference between the Autun and Oldham specimens ; 
for whilst the vascular b'tndles in the petiole of the former 
were shaped like a double anchor, in the latter they came 
nearly together and formed a circle; but he thought this 
difference scarcely sufficient to form another species. 
Dr. J. P. Joule, F.R.S., described some experiments he 
had been making on the polarization by frictional electricity 
of platina plates, either immersed in water or rolled together 
with wet silk intervening. The charge was only diminished 
one half after an interval of an hour and a quarter. It was 
ascertained both in quality and quantity by transmitting it 
through a delicate galvanometer. He suggested that a con- 
denser on this principle might be useful for the observation 
of atmospheric electricity. 
Proceedings — Lit. & Phid. Soc. — Vol. XI. — No. 10. — Session 1871-2. 
i 
