REV. W. THORP, B,A. — AGRICULTURAL GEOLOGY, ETC. 233 
dissented from the opinion that the Yorkshire Coal-field was a deposit 
of jungles, forests, peat bogs, and morasses of vegetables grown upon 
the spot. He argued that it was a deposit of matter drifted from a 
distance, and he asserted this after having accompanied Mr. Thorp 
in his travels. To a large portion of the tract under consideration he 
could bear ample testimony as to its accuracy. The Coal-fields of 
the North of England, such as Newcastle and Durham for instance, 
which he had la,tely examined, were most certainly the result of 
matter drifted from a distance. Professor Phillips begged to observe 
that when the facts or phenomena were self-evident geologists were 
willing to agree, but where they offered somewhat doubtful characters, 
then they were compelled to differ, and could be allowed to do so. 
The fact was he thought to a certain extent both theories were 
correct ; in some instances coal-fields were derived from vegetables 
which had grown on the spot, and in others they were the accumula- 
tion of vegetable substances transported from other localites by the 
actions of floods. Earl Fitzwilliam considered the students of geo- 
logy were too apt to draw hasty conclusions, as they were ignorant of 
the mighty power which had been at work in the formation of the 
crust of the earth. 
The following year Mr. Thorp presented another paper on " The 
Ventilation of Coal Mines." About this time several explosions had 
occurred, with considerable loss of life. Only a few days previously to 
his reading the paper, the Oaks Pit, near Barnsley, was destroyed, with 
a loss of 73 lives, and much public attention was directed to these 
casualties. Mr. Thorp stated that nothing could be more simple than 
the principle upon which coal mines are ventilated. Atmospheric 
air descends by one shaft, called the * down-cast ' shaft, is made to 
circulate through the subterranean workings, and to ascend at another 
shaft, the ' up-cast ' shaft. The ascending current of air is made 
lighter usually by a fire placed in the up-cast shaft, and the efficiency 
of the ventilation of the mine will be in proportion to the heat of this 
ascending current. It becomes, therefore, an object of the first 
importance to obtain a rapid and warm current of air in the up-cast 
shaft, and here occurs a difficulty not usually acknowledged by 
viewers and overlookers of collieries. To obtain good ventilation the 
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