Lenses of these high magnifying powers are sometimes sold by
spectacle-makers, for persons who have undergone an operation for
cataract. I have tried, but hitherto without much success, to arrange the
fittings by which the lenses are secured so that by a movement of the jaw
or by an elevation of the eyebrows, I could give the necessary adjustment
of the glasses, leaving my hands free for the purpose of swimming. (See
also, under "Fishing;' 'To see Things deep under Water.')
RAFTS AND BOATS.
Rafts.--Rafts of Wood.--Rafts are made of logs of wood, held together by
pairs of cross-bars, one of each pair lying above the raft and the other
below; then, the whole may be made quite firm by a little judicious
notching wherethe logs cross, and a few pegs and lashings. Briers,
woodbines, etc., will do for these. If the logs are large, they should be
separately launched into the river, and towed into their proper places.
Outriggers vastly increase the stability of a raft. The raft-fastening in
common use is shown in f. 1: it is a stout, little wand, bent over the
cross piece, and wedged into holes in the framework.
[Sketch of raft].
[Fig 1 and Fig 2 show fastening arrangements].
The rafts of European rivers are usually built on shore, and launched
into the water: three slides are laid for the purpose, on the sloping
bank of the river; upon these are laid the four poles, secured together
by their ends, which are to form the framework of the raft (fig.
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