90 Mr Forbes's Physical Notices of the Bay of Naples. 



that at this part of the scale it would require a reduction of 

 1°; I therefore placed the temperature at 182^.5. It was on 

 the 11th of December 1826. This observation is the more 

 valuable, that, as far as I know, it is the only one affecting 

 accuracy yet given to the world. Most authors have asserted 

 that the water boils ; * and Romanelli distinctly asserts that 

 its temperature exceeds 80° Reaumur, though it is obvious 

 enough he could never have tried it. Breislak,-f- with great 

 moderation, says, " La chaleur qui y regne a une grande in- 

 tensite ; Tobscurite du lieu, et la vapeur qui s'attache a la sur- 

 face de tous les corps, empechent de la mesurer avec precision, 

 mais elle passe les 60 degres de Reaumur." But 60° R = 167° 

 Fahr. so that Breislak comes below the mark. 



It is not surprising that the idea of so great a heat as this 

 should have been alarming to those unacquainted with the 

 powers of animal life to withstand intense heat, when we re- 

 flect that the time is not very long past when the experiments 

 of Blagden and Fordyce put this question in its true light. 

 The most intense heat, however, sustained by these gentle- 

 men \ seems to have been in dry air, which has far less effect 

 on the body than an atmosphere loaded with steam, which, 

 by condensing on the body, parts with a large share of its ca- 

 loric. These experimenters, however, found far less incon- 

 venience than they expected from the great temperature. 

 Their bodies when exposed to steam of a moderate tempera- 

 ture became inflamed, the pulse much quickened, but the heat 

 of the body little affected. In passing to the cold air they 

 felt little inconvenience, probably from the excess of moisture 

 and perspiration which defended the pores of the skin from the 

 rapid effects of cold. The degree of perspiration in the heat- 

 ed baths varied very much in different persons, and was 

 greater in the dry than vapour stoves. Dr Fordyce having 

 remained fifteen minutes in a vapour stove at a temperature of 

 130° (greatly lower than that of Nero's Baths,) his pulse rose 

 to 139, and he was much more affected than by dry air of a 

 greatly higher temperature, which he justly imputed to the 



* Hamilton, Ferber, OrlofF, Lalande, &c. 



-f- Cnvipanie, ii. 173. 



t Phil. Trans, vol. Ixv. iii. 484. 



