Geological Society. 67 



from Farnham, a well was dug in sand to the depth of 36 feet, and 

 one of the workmen on descending into it was instantly suffocated. 

 Fatal effects have also resulted from the accumulation of this gas in 

 wells in Maiden-lane, Battle-bridge, and at Applebury-street, near 

 Cheshunt. This gas is much increased, after long-continued rain, in 

 consequence of the swelling of the clay driving it out of the in- 

 terstices ; and it is diminished after a long drought. The preva- 

 lence of a north-east wind has been noticed by well-diggers to dimi- 

 nish the quantity of the gas, but the effect is ascribed by Dr. Mitchell 

 to the dry weather which usually accompanies the wind from that 

 quarter. The author also suggests, that if wells are to be dug in 

 dangerous districts, they should be undertaken when there is least 

 water in the ground, or from the beginning of July to October. 



The noxious gas in the Weald of Kent and Sussex is stated to be 

 sulphuretted hydrogen. 



November 20, 1839. A paper " On the origin of the vegetation 

 of our Coal-fields and Wealdens," by J. T. Barber Beaumont, Esq., 

 F.G.S., was next read. 



An examination of the fossil trees discovered on the line of the 

 Manchester and Bolton Railway* has confirmed Mr. Beaumont in 

 the opinion, that in no instance has the vegetation of the coal-fields 

 arisen from drifted trees sunk to the bottom of mighty rivers and 

 estuaries, but that it grew where it is found ; and he is further of 

 opinion, that the districts composing our present coal-fields were ori- 

 ginally islands. 



The principal objections of the author to the theory of the trans- 

 portation of the fossil vegetation are the following : 



1. The existence of a mighty river or estuary at the time of the 

 deposition of the coal-measures, would require the existence of a vast 

 continent of which there are no traces. 



2. The coal strata near Newcastle are 380 yards in thickness, and 

 consequently, the lowest strata must have been deposited^at the bot- 

 tom of a river or estuary, exceeding in depth, six times the mean 

 depth of the German Ocean. 



3. A continent producing such a river, it is reasonable to expect, 

 would have left an abundance of fossils on its surface, as well as at 

 the bottom of its great river ; but all the land for hundreds of leagues 

 around the coal and wealden formation swarms with the remains of 

 marine animals, and is clearly an ancient sea bed. 



4. In the coal-measures not a bone of a land quadruped is to be 

 found, or a large timber tree, with the exception of a few Coniferse. 



5. In order that the vegetation should have sunk to the bottom 

 of a deep river, it must first have decayed ; but the plants preserved 

 in the beds associated with the coal, present a freshness and perfec- 

 tion incompatible with such a condition. 



6. Drifted trees are stopped in deltas only from the shallowne'sa 

 of the water being insufficient to float them on ; we know of no de- 

 posits of trees in deep water. 



* See the Abstract of Mr. Hawkshaw's Paper, Proceedings, vol. iii., 

 p. 139 ; [or L. & E. Phil. Mag. vol. xv. p. 539. J 



F 2 



