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This experiment, which feetn’d at firft but mere 
food for curiofity, became in the interim very ufeful 
to us. By its means we fupplied our cold bath, and 
cooled our wines or water at pleafure ; which is vaftly 
agreeable to us in this burning climate. 
I intend, in our paffage to the Weft Indies, to 
found a mile deeper than I have done, having a fuf- 
ficient quantity of line. But I cannot attempt your 
method to find the depth of the fea, for want of ap- 
paratus. My bufinefs at prefent affords me very lit- 
tle time for fpeculation. However, I cannot omit 
obferving to you a phenomenon, which I faw laft 
night, and never before, that I remember ; and that 
was the two arches of the iris, with their colours 
diftindt, by moon-light. Having already prefumed 
much on your patience, and my leifure, 
I am, &c. 
Hen. Ellis. 
A Letter to the Prefident, fro?n Stephen 
Hales, D. D. F. R. S. 
S I R, Teddington, June 8, 1751. 
Read June *3.'!' HAVE here inclofed, at his defire, a 
I751, copy of a letter from Captain Ellis, 
who publifhed an account of his voyage to Hudfon's 
Bay. 
The bucket fea-gage, which he mentions, and 
which I provided for him, to find the different de- 
grees of coolnefs and laltnefs of the fea, at different 
3 depths, 
