DRY ROT IN SHIPS. 259
"cases the danger is augmented by stagnation of the moist air or
"moisture and increase of temperature. I have seen the Lycoperdon
"Carpobolus (of Linneus and E. Fungi tab. 22) a little Fungus that
"discharges a sort of capsule to a considerable distance like a shell from
"a mortar, grow on rotten damp wood both when exposed to frost
"out of doors and in a pine heat in the late Duke of Portland's hothouse
"at Bulstrode. There are few Fungi that will grow upon wood that is
''covered by water although that wood may be in a state of rapid
"decay.
"I have before insisted upon the propriety of avoiding all dark
"holes or corners where damp may get confined or where there is any
"difficulty of cleaning; I would in addition recommend that to dis-
"cover the earliest indications of the rot the Ship should be often
"cleaned and all suspicious parts examined with the Hygrometer.
"No place should be allowed to remain long without fresh air being
"introduced if the Hygrometer stands above 600°, if it be above 700°
"the air should be often changed or a current should be passed through
"or over the place until the Hygrometer return to the same degree as is
"indicated by it in the open air. If this operation be performed
"in dry weather it will be most effectual. The instrument should be
"allowed to remain a quarter of an hour in the neighbourhood of
"the most suspected wood16 and the appointed Officers should pay
"especial attention to the middle and lower parts and dark recesses or
"corners of Ships.
"There is no doubt but that Oak and Mahogany, some kinds of
"which I understand are now cheap, are good materials for the large
"and strong parts of ships where Iron is not convenient; Oak, more
"especially English, may become nearly as hard as Iron by age and
"proper attention. Deal of any kind is always comparatively soft and
''spongy, whatever precaution may be taken, and though it may be
''strong enough for some purposes, it is very apt to absorb water so
"should be as much avoided as possible, but most carefully where it is
"likely to be covered over. Its being splintery renders it an unmerciful
"act to use more than can be helped in Ships of war. I think also
"that the crowding many pieces together in place of one larger one is
"a bad thing.
"Every Englishman must feel grateful to your Honourable Board
"for the pains you have taken in your arduous trust. With the best
''hope that your endeavours may be crowned with the most brilliant
"success I remain
"Honourable Gentlemen
''Your very faithful and humble Servant
JAS. SOWERBY."
"2 Mead Place Lambeth 17th Feby. 1813."
Enquiries were made about the names and addresses of the
makers of hygrometers and eight months later Sowerby was
16 It would be. proper also to make allowance for the temperature in determining the degrees
of moisture (for the higher the temperature the lower the dangerous point on the instrument)
for which tables may be constructed as soon as the kind of hygrometer best adapted to the purpose
is determined on.