190 
PROCEEDINGS 1841 — 1848. 
to the light are drawn up, and the trees, if not thinned out, become 
too tall to be supported by the strength of their bole. ^Ir. Hammerton 
incidentally mentions some of the largest trees in the country, and 
awards the palm to the Cowthorpe Oak in this county, which, within 
eight feet of the ground, has a circumference of sixteen yards. This 
is by far the largest tree in the British Islands, and is said to be 600 
years old. 
Mr. Thomas Sopwith exhibited a model of the strata near the 
Coal and Ironworks at Ebbw Vale, in Monmouthshire, in which the 
workings of the successive beds were accurately laid down, and could 
be inspected with the greatest ease. Dr. Buckland, who was present, 
said that whoever saw such a model as this could not fail to under- 
stand the nature of a coal-field. Xow that we had the means it would 
be a sin on the part of the nation to neglect the opportunity thus 
afforded for making an accurate register of the state of our mining 
districts. If such registers had been kept of ancient workings in the 
principal coal-fields of England they would have been the means of 
preserving the lives of hundreds of miners, and have prevented the 
loss of an immense amount of property. 
Mr. B. Byrom, of "Wentworth, contributed a paper on the 
Reciprocal Propelling Powers of Fluids, and certain Rotary Machines 
upon each other. The object of this communication was to elucidate 
certain principles of action, and proper construction of machines 
which derive their motion from the oblique impulse of the atmosphere 
or water, and the construction of the sails of windmills are entered 
into with considerable detail. An important feature in this paper is 
the application of similar rotary machinery in order to propel boats 
through water, and with the aid of tin models which he had prepared, 
he showed that a screw propeller might be used in urging small boats 
through water with considerable celerity. The success attending his 
experiments in propelling upon water, induced him to turn his 
attention to the same principle to propel air, and he exhibited models 
which clearly illustrated the great capability of a wheel of this con- 
struction. By obtaining considerable velocity, he found he could 
readily cause a current of air to pass through a building at the rate 
of nine hundred to a thousand feet per minute, and he could not 
