[ 53 ] 
there are earthquakes without proportionable fub- 
fidences, there the caverns and dudfs under-ground 
remaining open and unchoaked, the fame caufe, 
which occafioned the firft, has room to revive and 
renew its ftruggles, and to repeat its deflations or 
terrors ; which is moft probably the cafe of Lifbon. 
I am, Sir, 
Your moft affectionate 
and obliged humble Servant, 
Wm. Borlafe. 
X. Experiments on applying the Rev. Dr. 
H ales ’ s Method of di filling Salt-water to 
the Steam-Engine . By Keane Fitzgerald, 
Efq> F. R. S. 
Read Feb. 17. N reading Dr. Hales’s account of 
purifying fait water, by blowing 
fhowers of air thro’, it occurred to me, that fome- 
thing of the kind might be applied with advantage 
to the fteam or fire-engine, by increafing the quan- 
tity of fteam, and confequently diminifhing the 
quantity of fuel otherwife neceftary. 
As the ftrength of fteam raifed from boiling water 
is always in a fluctuating ftate, and, by the beft 
experiments hitherto made, has never been found 
above T '- ftronger, or weaker, than air ; I was in 
doubt, whether fteam, produced by this method, 
would 
