76 SEVENTH REPORT—1837. 
in the passages being displaced by the water. Breeze followed breeze, 
as torrent succeeded to torrent, and soon the whole 20 miles of passages 
and railways were completely filled. Twenty-seven men were below, 
and, when the noise reached them, were totally unable to conjecture 
its cause, though danger of some kind was manifest. Four escaped 
under the guidance of Brennagh, an Irishman, by following the air- 
courses; Brennagh, himself, in the midst of all this fearful noise, per- 
plexity, and confusion, stopping in his progress, and going back 100 
yards to save an old man. These men passed over a distance of 3000 
yards in making their escape, and when they reached the spiral stair- 
case, all the other routes having there become stopped, the wind roared 
through it with such violence, that it was heard a quarter of a mile off. 
At this time Bland, the last man coming up, was buoyed up by the wind, 
and, just as he expected deliverance, a trap-door, caught by the cur- 
rent of air, closed upon him. He, however, was not dismayed, but at 
once punched a hole, when the valve opened, and he was actually 
blown out of the pit mouth*. 
On the Mud deposited by the Tidal Waters of the Severn, Usk, and 
Avon, and other phenomena connected with the Waters of these 
Rivers. By Joun Ham, of Bristol. 
The author, having described the peculiarities attending the vio- 
lent influx of the tide along the gradually contracting estuary of 
the Severn, till it finally produces the bore in that river, and rises 
to an extraordinary height in the Wye—observes, “This incessant 
agitation and conflict of waters naturally render them very turbid: 
that they do not readily mix when the fresh water is sent back by a 
high wave, or what may be called a wall of sea water, may be con- 
ceived; but where the Channel is wider, and its bottom full of in- 
equalities, it might be supposed that the mixture was more readily 
accomplished ; and so it is, for the regularity in its specific gravity 
at the same season of the year is great, as I have found it the same 
in the month of August in the present year, and in 1822, viz. 1020. 
This indicates that it is rather less than the specific gravity of the open 
sea or ocean, remote from rivers, which is found to vary from 1020 to 
1028. 
«<The bed of the Bristol Channel, on the Welsh coast, is much more 
shallow than on the opposite coast; therefore, a much greater space 
of the bottom is exposed to the rays of the sun on that side at low 
water. This will partly account for the superior temperature of the 
water on the Welsh coast, which I found to be 67° Fahrenheit in the 
month of August, and 65° only on the south-east side of the Channel, 
near the mouth of the river Avon. 
“To the shallowness of the water on the Welsh side must also be 
* Professor Sedgwick, having made some reflections on the lesson of caution 
afforded by this melancholy catastrophe, appealed to the Section in behalf of the 
gallant Brennagh, when 34/. were immediately subscribed. 
