1804.] 
account of which was diftin@ly laid be- 
fore the fociety, but which cannot be fuc- 
cefsfully repeated here without the aid of 
plates. From the firit ferics of thefe ex. 
periments he concludes, ‘* that all the 
heat which a hot body lofes, when it is 
expofed in the air to cool, is not given off 
to the air which comes into contaét with 
it, but that a large proportion of it efcapee 
in rays, which do not heat the tranfparent 
air through which they pafs, but, like 
light, generate beat only when, and where, 
they are ftopped and abforbed.” 
As the refults of various other experi- 
ments made with a view to determine the 
relative quantities of rays emitted from the 
furfaces of different fubftances, from liv- 
ing animals, dead animal matter, &c. we 
are informed that thofe fubftances which 
part with heat with the greateft facility, 
are thofe which aifo. acquire it moft rea- 
dily, or with the greateft celerity: and 
alfo that the greater the power is which 
an animal poffeffes of throwing off heat 
from the furface of his bedy, independent. 
ly of that which the furrounding air takes 
off, the lefs will his temperature be affect. 
ed by the occafional changes of tempera- 
ture which take place in the air; and tha 
Je{s will he be oppreffed by the intenfe 
heats of hot climates. 
It is well known, fays this philofopher, 
, that megroes and people of colour ‘fupport 
the heats of tropical climates much better 
than white people. Is it not probable 
that their colour may enable them to thraw 
off calorific rays with greater facility, and 
in greater abundance; and that it is to 
this circumftance they owe the advantage 
they poffefs over white people, in fupport- 
ing heat? And fhould it be true, that 
bodies are cooled, not in confequence of 
the rays they emit, but by the actions of 
the frigorific rays they receive from colder 
bodies, yet, as it bas been found by ex- 
periment, that thofe bodies which emit 
calorific rays in the greateft abundance, 
- are alfo moft affe&ted by the frigorific rays 
of colder bodies, it is evident that in a 
very hot country, where the air and all 
other furrounding bodies are but very 
little colder chan ‘the furface of the fkin, 
thofe who by their colour are prepared 
and difpofed to be cooled with the greateft 
facility, will be leaft likely to be opprefled 
by the accumulation of the heat generated in 
them by re{piration, or of that excited by 
the fun’s rays. 
From various experiments, related by 
the Count, we Jearn that calorific rays are 
thrown off in greater abundance from a 
black fuxface, than from one that was not 
Proceedings of Learned Societe’. 
327 
blackened: Hence he thinks meafures 
might be taken for the prefervation of the 
health of Europeans who quit their na- 
tive climate to inhabit hot countries; at 
leaft, under fuch circumftances, he fays, 
nothing fhould prevent him blackening his 
fkin, or, at Jeaft, wearing a black fhirt in 
the fhade, and efpecially at night; in 
order to find out, if, by thofe means, he 
could render himfelf more comfortable, 
Several favage tribes which inhabit very 
cold countries, befmear their fkins with 
oil, which gives them a fhining appear- 
ance, and reflects the rays of light very 
copioufly from their furface. « May not, 
therefore, the frigorific rays, which arrive 
at the furface of their fkin, be alfo refle&- 
ed by the highly polifhed furface of the 
oil with which it is covered?” In that 
cafe, inftead of defpifing thefe poor crea- 
tures for their attachment to a ufeleS and 
loathfome habit, we fhould be difpofed to 
admire their ingenuity; or rather the 
goodnefs of their invifible guardian and 
inftruétor, who teaches them to like and 
to practife what he knows to be ufeful to 
them. 
From other experiments Count Rum. 
ford is difpofed to believe that the Hotten- 
tots derive advantages from befmearing, 
themfelves, exaétly fimilar to thofe which 
negroes derive from their black colour: 
and he thinks that a knowledge of the 
phyfical advantages which thole favages 
derive from fuch practices, may enable us 
to acquire the fame advantages by em- 
ploying more elegant means. ‘* A know- 
ledge of the manner in which heat and 
cold are excited, would enable us to take 
meafures for thefe important purpo‘es 
with perfect certainty : in the mean time, 
we may derive much ufeful information, 
by a careful examination of the pheno- 
mena which occafionally fall under ous 
obfervation. 
“¢ Tf it be true that the black colour of 
a negro, by rendering him more fenfible 
to the few frigorific rays which are to be 
found in a very hat country, enables him 
to fupport the great heats of tropical cli- 
mates without inconvenience, it might be 
afked, how it happens that he is able to 
fupport, naked, the direct rays of a burn- 
ing fun? 
‘* Thofe who have feen negroes expoled 
naked to the fun’s rays in hot countries, 
muft have obferved that their f{kins, in 
that fituation, are always fhining, An gil 
exudes from their fkin, which gives it 
that fhining appearance, and the polifhed 
furface of that oil refie&s the fun’s calo- 
rific rays. If the heat be very intenfe, 
fweat 
