III. 
ACRE. 99 
to many other causes, proves fatal, by its exha- ^'^J;\^- 
lation. This is so true, with regard to antient 
ruins in the south of Europe, that the inhabitants 
of the neighbouring districts generally caution 
strangers against the consequences of visiting 
them during the summer months ; consequences 
far more dangerous than any other accident to 
which travellers may fancy themselves exposed 
in foreign countries. By the introduction of 
these remarks, the author is sensible of repeating 
observations already made% but the importance 
of the caution they convey cannot be too much 
enforced. Places infected by such dangerous 
vapour may be distinguished, at the setting or 
rising of the sun, by thick and heavy mists of a 
milky hue ; these may at that time be observed, 
hovering, and seldom rising high above the 
soiP. The mildest diseases inflicted by this 
kind of air, are quartan and tertian fevers ; and 
sometimes it occasions instant death. Th@ 
inhabitants of the Gulph of Sdernum and the 
Coast of Baia, as well as those resident in the 
Pontine Marshes", suifer violent contraction of 
(2) See Chaji. VIII. of the Third Volume, p. 290, 
(3) The air of any place is seldom salutary where flies are found iu 
great abundance. Another criterion of the sources of mephitic 
exhalation is, the appearance of the nrinxh phragmites. This plant, 
in warm countries, may g'enerally be regarded by travellers as " a 
warning hnoy." 
(4) \ mal-arin prevails at Rome during summer; particularly in 
the Transtihertine suburbs of the city. This seems alluded to by 
riinif, 
