JB/538/239/001

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Plymouth Dock Tuesday Septr 1778

Mr Loyd returned to Pl this morning & I have got both waistcoat & Bank note
the latter was very acceptable as I had but 2 or 3 shillings left and owed a
small Tal Taylor's Bill. My project for covering ships bottoms plagues me
exceedingly I neither know how nor where I shall make the first experiment.
I wish much that I could try it here, because I wish to stay here 2 or 3
weeks on other accounts. I will ower have a thin piece of wood & attd different planed? north
composition as different part and I'll stick the tinfoil on different parts of
it with different compositions. I havenot much doubt but that the tinfoil
may be made to stick close enough to the composition, what I fear most
is the whole pealing off together as pitch is apt to do when the wood it
was laid on becomes water soaked. The friction of the water alone
on the bottom of a ship will no doubt wear the tinfoil through in time
but in how long a time remains to be tried: it may be thicker that that usually
made as to coat electrical jam with.— Another cause has just now
struck me of why pitch &c must be apt to fall off from a ships bottom
where under water. You may perhaps remember when we were trying
air experiments in a wooden kind of cistern, that a vast number of
air bubbles were forced out of the cells by the might of the water out of the little cells on the
inside of the wood by the pressure of the water. all the inside of the trough
bottom & sides were covered with these little bubbles and if we brushed them
off more were formed till all the cavities that were within the
reach of the pressure of the water were filled with the water, till in that
the wood was water soaken. The surface of a ships bottom on account
of it depth under water is pressed with much more force than our
cistern was, consequently the air contained in the little cells of the
wood is much more bent on making its escape: this it cannot do
without finding a passage through the unporous composition with which
the bottom is covered. Nerthed indeed can the water be pressed in so as to

Identifier: | JB/538/239/001 "JB/" can not be assigned to a declared number type with value 538.
Date_1	1778-09-08	Marginal Summary Numbering
Box	538	Main Headings
Folio number	239	Info in main headings field
Image	001	Titles
Category	Correspondence	Number of Pages
Recto/Verso		Page Numbering
Penner	Samuel Bentham	Watermarks
Marginals		Paper Producer
Corrections		Paper Produced in Year
Notes public		ID Number
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