a better chance to settle. His argument
was that the conditions should be changed; by narrowing the stream and
giving it less fall, gold, which was incapable of amalgamation on the
wide plates, would be saved. We finally put one in, and it proved
so successful that we now have one at the end of each table. The
per-centage recovered on the sluice plates, of the total yield, varies,
and has been as follows:--October, 9.1 per cent; November, 6.9 per cent;
December, 6.4 per cent; January, 4.3 per cent; February, 9.3 per cent."

MEASURING INACCESSIBLE DISTANCES

To ascertain the width of a difficult gorge, a deep river, or
treacherous swamp without crossing and measuring, sight a conspicuous
object at the edge of the bank on the farther side; then as nearly
opposite and square as possible plant a stake about five feet high, walk
along the nearer margin to what you guess to be half the distance across
(exactitude in this respect is not material to the result), there plant
another stake, and continuing in a straight line put in a third. The
stakes must be equal distances apart and as nearly as possible at a
right angle to the first line. Now, carrying in hand a fourth stake,
strike a line inland at right angles to the base and as soon as sighting
over the fourth stake, you can get the fourth and second stakes and
the object on the opposite shore in line your problem is complete. The
distance between No. 4 and No. 3 stakes is the same as that between No.
1 and the opposite bank.

TO SET OUT A RIGHT ANGLE WITH A TAPE

Measure 40 ft. on the line to which you wish to run at right angles, and
put pegs at A and B; then, with the end of the tape held carefully at
A, take 80 ft., and have the 80 ft. mark held at B. Take the 50 ft. mark
and pull from A and B until the tape lies straight and even, you will
then have the point C perpendicular to AB. Continue straight lines by
sighting over two sticks in the well-known way.

_Another method_.--Stick a pin in each corner of a square board, and
look diagonally across them, first in the direction of the line to which
you wish to run at right angles, and then for the new line sight across
the other two pins.

A SIMPLE LEVELLING INSTRUMENT

Fasten a common carpenter's square in a slit to the top of a stake by
means of a screw, and then tie a plumb-line at the angle so that it
may hang along the short arm, when the plumb-line hangs vertically
and sights may be taken over it. A carpente