e. When he got into the position which
enabled him to just see the tree top over the top of the stick he
again had a right-angled triangle with tree as perpendicular, his
eye's distance away from the trunk, the base, and the line of
sight the hypotenuse. He could measure the base line along the
ground and knew it must equal the vertical height, and he could do
this without reference to the sun. It was an ingenious application
of the well known properties of a right-angled triangle. --Railway
and Locomotive Engineer.

** White Putty to Black [376]

White putty on a black window frame can be made to harmonize by
rubbing the fresh putty with a piece of cotton dipped in
lampblack.

** Using Sandpaper [376]

Sandpaper may be kept from slipping under the hand by chalking the
back.

** An Interesting Electrical Experiment [377]

Anyone possessing a battery having an electromotive force of from
4 to 20 volts can perform the following experiment, which is
particularly interesting on account of the variation of results
with apparently the same conditions.

Immerse two pieces of brass in a strong solution of common salt
and water. Connect one piece to the positive wire and the other to
the negative, taking care that the brass pieces do not touch each
other.

After the current has passed one

[Illustration: How Wires are Connected]

or two minutes, the solution will become colored, and if the
process is continued a colored pigment will be precipitated. The
precipitate varies considerably in color and may be either yellow,
blue, orange, green or brown, depending on the strength of the
current, the strength of the solution, and the composition of the
brass.

** Novelty Chain Made from a Match [377]

The accompanying engraving shows what is possible to do with a
penknife.

[Illustration: Lay a Match on the Picture]

A small chain composed of several links was cut from the wood that
forms the match.

** Keeping Doors Closed [377]

Glass doors in bookcases may be kept from swinging open by boring
a hole, about 1/4 in. deep, either at the top or bottom in the
edge of the door, 2 in. from the closing edge, and inserting an
ordinary cork, allowing a small portion to project and rub on the
facing.

** Restoring Broken Negatives [377]

Whoever has the misfortune to break a valuable negative need not
despair, for the damage can be repaired most effectively. In case
the negative be broken in