[ ?io ] 
This laft Obfemtion may be applied to the cooling 
of Liquors where no Ice is to be had 5 for there is 
hardly any Place, but what has Wells: Now the Wa- 
ter of a Well moderately deep, wants about eight or 
10 Degrees of the Cold of Ice > and Sal Ammoniac 
being cool'd beforehand in the Well, will, by mixing 
with fome of the Water of that Well, come very 
near to the Cold of Ice . 
III. jin Obfervation of the Magnetic Needle 
being fo affe&ed by great Cold, that it 
would not traverfe 3 by Capt . Chrifto- 
pher Middleton, F. R. S- 
I N a Letter which was publish'd fome Years ago in 
the Bhilofophical Tranfaffions , (N° 41 8.) 1 made 
Mention of a ftrange Phenomenon relating to the 
Sea-Compafs, which 1 had frequently obferved, when 
we were among the Ice in Hudfons-Bay $ to wit, 
that the magnetic Virtue of the Needle was fo far 
loft or deftroyed, that it would not traverfe as ufual, 
even when the Ship was in a conftderable Motion : 
And in my Voyage thither laft Year, I obferved our 
Compafs would not move at all, any longer than the 
Quarter-Mafter kept touching it. We had then much 
Snow on the Land, and many Ifles of Ice around us, 
and the Sea not very fmooth : I order'd one of the 
Compafles to be brought into the Cabin, but did not 
find it any better, till it had flood near the Fire about 
a Quarter of an Hour, and then it began to traverfe 
very well ? I then order'd it to be placed in the Bin- 
nacle, 
