essential to explorers to have a sufficient quantity in reserve. Tar is
also of very great use in hot dry countries for daubing over the wheels,
and the woodwork generally, of wagons. During extreme heat, when the wood
is ready to crack, all the paint should be scraped off it, and the tar
applied plentifully. It will soak in deeply, and preserve the wood in
excellent condition, both during the drought and the ensuing wet season.
(See "Tar, to make.") It is not necessary to take off the wheels in order
to grease the axles. It is sufficient to bore an auger-hole right through
the substance of the nave, between the feet of two of the spokes, and to
keep a plug in the hole. Then, when you want to tar a wheel, turn it till
the hole is uppermost, take the plug out, and pour in the tar.

Breaks and Drags.--Breaks.--Every cart and wagon in Switzerland, and,
indeed, in most parts of the Continent, has a break attached to it: the
simplest kind of break is shown in fig. 2, which represents a cart tilted
upwards. Fig 1 shows the break itself; fig. 2 explains how it is fitted
on to the cart. [Fig 1.] It will easily be understood how, by tightening
the free end of the cord, the break is pressed against the wheels. The
bent piece of iron shown in fig. 2, by which the bar of the break is kept
in its place, may be replaced by a piece of wood, or even by a thong of
leather. Every explorer's wagon should be furnished with a break.

[Fig 2].

A simple break, used in Italy, in some parts of England and probably
elsewhere, is shown in fig. 3. A rail is lashed to the body of the cart,
both before and behind the wheel, and is made to press against the wheel.
Either both lashings can be tightened at the same time, as at A, A; or
only one of them, as at B. When the lashings are loose, the rail rests
partly on the nave of the wheel and does not sensibly interfere with its
movement.

[Fig. 3].

Other Means of Checking a Wagon on a Hill-side.--In going down a steep
hill a middling-sized tree may be felled, and its root tied to the hind
axletree, while its branchy top sweeps along the ground, as is seen in
the lowermost wagon in the sketch. [Sketch of horses and wagons on hill]
In the south-west of France the leaders of the team are unharnessed and
taken to the back of the wagon, to which the collar of the front horse is
made fast; in this way they can aid the horses in the shafts. The same
plan may be seen practised hourly in the Strand in Lon