Suinmii of the Penh of Teneriffe. 37 



^as. What surprised me most, was to find close to the in- 

 crustations of sulphur, which it terms in a short time, real 

 opal in thin mamellous plates. 



Having ascertauied the discovery of a formation so sin- 

 gular, I ascended, to terminate by barometric observations. 

 I shall here mention only the first, because the rest oave me 

 the same results in the calculation, a few differences more 

 or less excepted. At eight o'clock, at the distance of a 

 toise and a half from the summit, the barometer was at 

 18 inches 4 lines, and Reaumur's thermometer at 6*9 de- 

 grees. At the same hour, Mr. Little, an Englishman, who 

 observed at the port with excellent instruments^ the preci- 

 sion of which I had verified, found the barometer at 23 

 inches 5-6 hues, and the thermometer at 19-9 degrees: 

 the station was seven toises above the level of the sea. The 

 result of these data, corrected accordmg to Deluc's method, 

 and then increased by eight toises and a half, makes the 

 height of the peak to be 1901*2 toises above the level of 

 the sea. 



This is far from the height of ten Italian miles, assigned 

 to it by Ricciolo and Kircher ; and the latter is nothing in 

 comparison of ihc 15 marine leagues ascribed to it by Tho- 

 mas Nicols. Why then should people convert into fabu- 

 lous wonders every thing great and curious produced by 

 nature ? Do they imagine that by every thing they add in 

 their extravagant accounts they iiicrease the feeble merit of 

 having seen them ? 



What has been said in regard to the intensity of the cold, 

 the weakness of spirituous liquors, and the difficulty of re- 

 spiration on the peak, is not more correct. In a word, I 

 have several times found by experience that the opinion 

 generally received in this respect is more thg.n exagq;erated. 

 f assure you that the cold was very supportable ; that liquors 

 had lost none of their force 5 that the hydro-sulphureous 

 vapours* were not injurious to respiration; and that we 

 ■suffered no inconvenience from the rarity of the air, though 

 it obliged us to make frequent pauses on approaching the 

 summit. In the last place, what has been said, and often 

 repeated, in very modern works respecting the appearance 



* The author means aquoso-sul/'hurrons, since he says that the vapours 

 arc composed only of pure water and sulphur. This proves, as I have 

 already observed in the preliminary discourse in the Journal dc Physique, 

 year 9, thai wlien we wish to express the combinations of inflammable 

 j^js With suipliurand other sut)St;mccs, we ought not to say hycho-iulphu- 

 icoui but hyrii ry^fno- sulphmrous , according to the principles of t.ic new 

 nomenclature. — Note oj Dclumfi'-'-'i/'. 



C 3 ul" 



