[ 4S5 ] 
to obfer\’'e, that, during my reildence in that quarter of 
the globe, I never faw any natural ice. I cannot declare 
that the thermometer has not defcended to the freezing 
point during the night, becaufe I never made the necef- 
lary obferyations ; but the water in every other lituation, 
excepting in the pans, has not appeared to be in a freez- 
ing ilate. The climate may probably contribute in 
fome meafure to facilitate the congelation of water, when 
placed in a iituation free from the heat of the earth, fince 
thofe nights in which the greateft quantity of ice has 
been produced, were, as I before obferved, perfed:ly fe- 
rene, the atmofphere fliarp and thin, with very little 
dew after midnight. Many gentlemen, now in England, 
have made the fame remarks, in their frequent vilits 
with me to the ice-pits. The fpungy nature of the 
fugar-canes, or ftems of the Indian corn, appears well 
calculated to give a palTage underthe pans to the cold air; 
which, a6ting on the exterior parts of the velTels, may 
carry off by evaporation a proportion of the heat. The 
porous fubftance of the veffels feems equally well qua- 
lified for the admillion of the cold air internally; and 
their Iituation being full a foot beneath the plane of the ' 
ground, prevents the furface of the water from being ruf- 
fled by any fmall current of air, and thereby preferves the ^ 
congealed particles from difunion. Boiling the w'ater • 
is efteemed a neceffary preparative to this method of con- 
gelation ; but how far this may be confonant with philo- 
fophical reafoning, I will not prefume to determine 
(a) See Part i. Art. xUl. 
Nn 
VoL. LXV. 
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