British Association. 289 
“ On the Result of Reductions of Curves obtained from the Self-record- 
ing Electrometer at Kew.” By Professor W. THomson. 
«On the Mathematical Theory of Plane Water Lines.” By Professor 
RANKINE. ‘ 
“On a certain class of Mathematical Symbols.” By Mr W. H. 
RUSSELL. 
“On a Mercurial Air-Pump.” By Mr J. Swan. 
L’Abbé Moreno exhibited the following instruments:—A Free Air 
Barometer, by the Abbé Jeannon; a Metallic or Holosteric Barometer, 
by M. Naudet; a New Micrometer, by M. H. Soleil. 
L’Abbé Moreno also exhibited Specimens of Telegraphic Facsimiles, 
produced by Casselli’s method. 
L’Abbé Moieno communicated a paper by M. Oudry on Galvanic 
Copper and its Applications. 
“On a New Marine Barometer, and on a Maximum Thermometer with 
a New Scale.” By Mr W. Symons. 
“Interim Report on the Vertical Motion of Currents of Air.” By 
Professor HENESSY. 
““On the Proof of the Dioptric and Actinic Quality of the Atmosphere 
at a High Elevation.” By Professor Piazzi Smytu. 
Section B.—CHEMICAL SCIENCE. 
President—Professor A. W. WILiLIAMson. 
“© On Fire-Clay Goods.” By Mr J. Cowen, jun.—Fire-clay is obtained 
in large quantities in the two counties of Durham and Northumberland. 
It usually lies beneath the Coal Measures in layers, varying in thickness 
from twelve inches to five or six feet. It is found in most abundance, 
and in the best quality, beneath the coal used for coking and manufactur- 
ing purposes. Silica and alumina are the two substances of which fire- 
clay is chiefly composed. 
The trade in fire-clay goods is of comparatively recent origin. Its 
progress at first was slow, but during the last forty years it has extended 
rapidly, and is still on the increase. The extension during the last 
twenty-five years has been especially marked and important. Fire-bricks 
were first made on the Tyne about one hundred years ago. 
For many years all that were made were consumed in the manufactories 
in the neighbourhood. Slowly but gradually the trade increased, and the 
goods made were sent in larger or smaller quantities to different parts of 
the United Kingdom, and to some of the chief ports in Europe and the 
British colonies. The extent of the trade in 1838 was as follows :—The 
number of bricks manufactured at that time per annum was about 
7,000,000. The local consumption then was about 2,500,000. The 
quantity sent to other parts of the United Kingdom was about 3,000,000, 
and the quantity exported was about 1,500,000. The extent of the trade 
at the present time is as follows :— 
' Number of Fire-bricks made per annum about ......... 80,000,000) 
The local consumption is estimated at ...........s.seeeeee- 43,000,000 
The quantity sent to other parts of the United King- 
POW US BS MALE Ab. in ec car's is kgedoevs oe cn octuaaw enema \ 27,800,000 
PG he, ibamtlty, Cx POMCE Mess a sesh caer a dacledeadrs selew ea oles 9,500,000 
