DRY ROT IN SHIPS. 263
cures—quacks, practical men, and politicians rivalling each
other in their love of country and hope of reward. Few as yet
realised that fungi were the cause of the rot and not the result
of it. It must not be overlooked, however, that there were
many measures undertaken by the government to ensure and
prolong the durability of timber, before and after it was worked
into ships and these measures were often kept secret. Knowles
gives accounts of several of these. "At the latter part of the
seventeenth, and at many periods in the eighteenth century,
immersion of timber, at some places in fresh, and at others in
salt water, has been practised in this country by the directions
of the Navy-board at large, or of the Surveyors of the Navy ;
it gradually grew into disuse, but why that mode was altogether
discontinued does not appear ; it has, however, been renewed
within the last few years, by putting the sided and converted
timber and plank cut from English oak, for at least three months
into fresh water at Deptford and Woolwich, and into salt water
at all other dock-yards" (1821).
Common salt applied in large quantities was often tried.
Thus Jackson in 1767 recommended as much of this "mixed
with lime, copperas, alum, epsom-salts and pearl-ashes, into
sea-water, as it would hold in solution." Between 1768 and
1773 nine sail of ships of the line were built and a great number
of frigates constructed and repaired with timber which had
been pickled in this way. The keel of the Intrepid which had
also been treated in 1767 was found to be rotten in 1770 and a
comparison of treated and non-treated timbers was favourable
on the whole to the latter. So jealous were the workmen of
that time, of the interference of any persons in endeavouring to
increase the durability of ships, that they raised an outcry
against the method, stating that in the use of the materials,
and in working the timber, they were subjecting themselves
to being poisoned : the experiments had to be stopped until the
College of Physicians certified the materials as innocuous.
Quick-lime was also tried. This was recommended by White
and as the frigate Amethyst was just building it was ordered that
the timbers of the frame of the larboard side and half of the
beams should be treated. She was launched in 1799: when
examined for repair in 1809 it was found that the treated
timbers were more defective than the untreated.