0/J the spontaneous Injlammatioti of Coals. 447 



pit at Brora in Sutherland, in the North of Scotland, which hap- 

 pened last Summer, of which mention is made in an anonymous 

 paragraph in p. 314, of your April number, did not happen 

 through any peculiar property of these Coals, occasioning their 

 spontaneous combustion, as is there asserted, but happened, not 

 on the pit-liHl, as any one reading this loose and extraordinary 

 notice might have supposed, but below, in the works, and is said 

 by my Correspondent, to have been solely occasioned by the neg- 

 lect of preserving proper air-gates therein, as I will mention below; 

 by which neglect, inflammable gas was accumulated, although the 

 same is evolved in very small quantities only, in these works, and 

 the accidental firing of this gas, set the gob or waste Coals and 

 rubbish on fire, that had been improperly left in loose heaps in 

 the works; but which was very soon extinguished, and the 

 works soon after resumed, instead of the Pit remaining shut up 

 six or seven mouths after the event, " partly on account of this 

 peculiar property of the Coal," L e. of spontaneous deflagration, 

 as is there asserted. 



In your xxxixth volume, p. 337, an account is inserted, of the 

 boreing which preceded the sinking of the present Pits at Brora; 

 and in vol. xlii. page 53, it is mentioned, that the workings of 

 Coals at luver-Brora (or iMouth of the Brora Piiver) connnenced 

 in 1598; it seems rather surprising therefore, to see the con- 

 trary opinion to there being any Coals north of the Tay, again 

 revived in your work, and represented as not proved to be un- 

 founded, until the discovery about two or three years ago !. 



As this is the most nortiiern Coal-field known in Britain, and 

 is in the near vichiity of mountains containing Granite, I have 

 thought that the following account of it may not be unacceptable 

 to your Readers. Accounts are preserved iii Sir Robert Gordon's 

 history, which I saw at Dunrobin, in 1812, that Coals were first 

 wrought on the shore S of the mouth of the Brora River, by 

 Jane Countess of Sutherland, in the reign of Queen Elizabeth, 

 in 1598, and where she erected Saltrworks*; also that iu 1G14, 



It furnislies a curious proof of the progressive rise of the Sea, of which 

 I have had similar proofs on evtry coast of Britain, that the remainiiiK 

 walls of this old Salt-house are ivashed n»w to a considerable hci;:ht by tiie 

 ordinary Tides, which niostU- flow hi<rher than the tops of the firc-p'/accs, 

 which are still visible, on which the salt-pans stood! and the tops of the 

 Coal-pit hillocks that were made at tiiis period, are most of tlicin since co- 

 vered by the sia-beach. On the shore at Mostyn, in Flintshire in North 

 Wales, the I'itssunk about the year 1640, in which the rire-danip explosion', 

 l^uppencd which are recorded in the Phdosophicul Transactions, No. i;!ti. 

 and where the water-wheel and chain pumps were used, that were drawn 

 \n J(581.,and have been since oi)<jiaved in Mr. Pennant's" .Accnint of Holy- 

 well and VVhifoid," h»ve now long had their topi covered, by nluiuA eveiy 

 I ide !. 



