[ 33 + 3 
. ments, for I have frequently found that they lead 
to the thing fought for. And by the like clue of 
reafoning and experimenting, there is the greateft 
probability, that, we lhall fucceed in another very 
important refearch, vizi. the preferving much longer 
from decay the timbers of fhips laid up in ordinary 
in harbour. For, as we are allured by daily experi- 
ence, that the decay is wholly owing to damp, clofe, 
confined, putrid, corroding air ; fo the only remedy 
for this evil is the frequently changing the air 
among the timbers, by plentiful ventilations ; which, 
we find, by happy experience, can be efie<fted to fuch 
a degree, as gives reafonable hopes, enough to encou- 
rage our farther trials and refearches. 
4f. Captain Thomfon, of the Succefs Frigate, in 
his letter to me, dated London, Sept 25, 1749, fays, 
“ That, during the ventilation, the lower-deck 
‘‘ hatches were commonly kept clofe lliut; by 
“ which means the air was drawn down into the 
“ hold, from between the decks, through the feams 
“ of the ceiling, along the timbers of the Hiip ; by 
“ which means we found the foul air foon drawn 
“ off from between decks. Our rule for ventilat- 
“ ing was for half an hour every four hours : but 
“ when the ventilating was fometimes negled:ed for 
eight hours together, then we could perceive, efpe- 
“ cially in hot weather, a very fenfible difference by 
‘‘ that fhort neglect of it ; for it would then take a 
“ longer time to draw off the foul air. Our general 
rule was, to work the ventilators till we found the 
“ air from them fweet. We all agreed, that they 
“ were of great fervice ; the men being fo fenfible 
‘‘ of the benefit of them, that they required no 
“ driving 
