1823.] Scientific Intelligence. 311 



dent will excuse me for requesting you to permit me, through the 

 same medium, to express my doubts as to the accuracy of his informa- 

 tion respecting the place from whence the specimen he so minutely 

 describes originally came. 



First, I would ask, whether he himself met with the specimen in 

 question at the quarry? If so, in which of the quarries was it found? 

 As there are many at Cat-Down, all of which I have frequently and 

 carefully examined, without ever finding in them, or in any others, 

 from the Dock Yard to the Ferry House at Cat-Down, quartz in mass, 

 independent of galena, and the other substances composing the stone. 



Secondly, if your correspondent did not find the specimen himself, 

 but purchased it with others, I would beg of him to compare it with 

 such as he knows to be the legitimate produce of our lime rocks ; and I 

 think he cannot fail of remarking the great dissimilarity, if not the total 

 want of any family likeness between them. And then let him reflect 

 how little dependance is to be placed on the veracity of those who 

 generally have such articles for sale ; and whose duplicity, art, or igno- 

 rance, I have daily opportunities of detecting. 



I would further state, that I have in my possession a specimen so 

 similar to the one above-mentioned, that I should almost be tempted 

 to say, that both came from the same place. Mine is certainly from 

 one of the mines in the vicinity of Tavistock, where the mixture 

 of quartz, galena, &c. &c. is frequent and often curious. 



I will only add my sanguine expectation that this will meet with a 

 candid reception, and an early place in your Annals, and conclude in 

 the last words of my own publication ; " that it will give me real plea- 

 sure at all times to receive an)' information from others, whose personal 

 knowledge and actual researches may enable them to throw any new 

 light on the subject of these pages." 



I remain, Sir, your obedient servant, 



Richard Henxah. 



**• The Editor is enabled to state, in reply to the foregoing letters, 

 and in order that the question to which tney relate may be decided, 

 that the small specimen described in the notice on the subject, inserted 

 in the Annals for February last, was purchased in the latter part of 

 September, 1822, with specimens of limestone and of stalactite unques- 

 tionably obtained from the Plymouth rocks, of Edmund Moss, quarry- 

 man, at Cat-Down. The author of the notice certainly has not mis- 

 taken calcareous spar for quartz, as a paragraph in Mr. Prideaux's letter 

 implies him to have done. 



V. On the Depression of the Barometer in Dec. 1821. 

 13y Mr. A. Edwin. 



The following observations on the extraordinary depression of the 

 barometer in Dec. 1821, were made in Owen's-row, near Islington, by 

 Mr. A. Edwin ; and have been communicated by him, in compliance 

 with the request of Prof. Brandes, inserted in the Annals for October 

 last. The basin of the barometer is situated about 40 feet above the 

 bed of the New River, which runs before the house. 



On Dec. 1 1 , the barometer was at 30 13 inches, and thence gradually 

 descended, with some slight intermediate elevations, until it fell to 

 2874- inches on the 24th at 8 a. m. 



