through a height of one inch in twenty-four
hours. The Admiral proposed to fix a number of tubes side by side in a
frame below the mass to be lifted, preferring to use zinc tubes of from
two or three inches in diameter, and of about one foot high. Thus, in the
small space of a cubic foot, a large number of tubes (thirty-six in the
one case, sixteen in the other) could be made to act simultaneously; the
force of the stroke could be increased by arranging a number of frames
side by side, or the length of the stroke could be increased by building
the frames in a series one above the other. I have elsewhere described
how wetted seeds may be used to restore the shape of a battered flask
either for holding water or gunpowder (pp. 230).
Parbuckling.--A round log or a barrel should be rolled, not dragged; and
many irregularly-shaped objects may have bundles of faggots lashed round
them, by which they become barrel-shaped and fit to be rolled. In these
cases, parbuckling doubles the ease of rolling them; one or more ropes
have one of each of their ends made fast in the direction to which the
log has to be rolled, while the other is carried underneath the log,
round it, and back again. By pulling at these free ends, the log will be
rolled on. An equivalent plan, and in some cases a more practicable one,
is to make fast one end of the rope to the log itself; then, winding the
rope two or three times round it, like cotton on a reel, to haul at the
free end as before.
Pages:
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452