68 Dr Thomson on a spontaneous emission of Gas. 



from the place where the gas was burning. The rivulet 

 when I visited the place was swollen and muddy, so as to pre- 

 vent its bottom from being seen. But the gas issued up 

 through it in one place with great violence, as if it had been 

 in a state of compression under the surface of the earth ; and 

 the thickness of the jet could not be less than two or three in- 

 ches in diameter. We set the gas on fire as it issued through 

 the water. It burnt for some time with a good deal of splen- 

 dour; but as the rivulet was swollen, and rushing along with 

 great impetuosity, the regularity of the issue was necessarily 

 disturbed, and the gas was extinguished. 



There is a thin bed of very fine-grained blue limestone in 

 the immediate neighbourhood, which had been wrought for- 

 merly a little to the east of the field where the issue of inflam- 

 mable gas is at present observed. During the course of last 

 summer, Mr William Dickson began to work this lime-bed 

 about three quarters of a mile to the south of the Cumbernauld 

 road. The limestone bed is about five feet thick, and, like all 

 the other beds in this immediate neighbourhood, dips to the 

 north-east, just in the opposite direction that the beds a 

 little to the west and south take ; all of which dip towards the 

 Clyde. No doubt the dip has been altered by the interven- 

 tion of some greenstone dike ; and indeed greenstone may be 

 seen a little to the west ; but neither the weather nor the state 

 of the country permitted me to trace the connection between 

 the greenstone and the dip of the strata. 



A good section of the strata is presented by the railway 

 that has been lately made directly to the east of the rivulet, 

 and which passes through a tunnel immediately under the 

 Cumbernauld road. This section presents the usual coal 

 metals, slate- clay, limestone, coal, shale. Figure 2 of Plate 

 II. presents a rude outline of the position and relative thick- 

 ness of the different beds. The uppermost bed of slate- 

 clay, about twenty feet thick, is composed of innumerable thin 

 strata of slate-clay, some of them blue and some black, like 

 shale. The limestone immediately under the slate-clay is five 

 feet thick. Next comes a bed of coal one foot thick. Below 

 the coal is a bed of slate-clay of unknown thickness, as it has 

 not been cut through. These beds, (if we make allowance for the 



