f
binding-posts, we shall give them the general name of binding-posts.

APPARATUS 40.

_58. Binding-Post._ About the simplest form is a screw, or a nail with a
flat head. The bare wire may be placed under the head of the screw or
nail before forcing it entirely into the wood. This will keep the end of
the wire in place, and another wire may be joined electrically to the
first by merely touching it to the screw-head, or by placing it under
the screw-head.

APPARATUS 41.

_59. Binding-Post._ Fig. 26. This consists of a screw and a copper
washer or "bur." The screw is a "round-headed brass" one, 5/8 in. long,
number 5 or 7. The copper burs are No. 8, and fit nicely around the
screws. By using 2 burs instead of 1, several wires may be easily joined
together at one point. Scrape the covering from the ends of the wires,
and place them between the burs.

[Illustration: Fig. 26.]

APPARATUS 42.

_60. Binding-Post._ Fig. 27. A coiled spring serves very well as a
connector. One end should be fastened to the apparatus, as shown, by
clamping it under a screw-head. The other end of the coil should be
pulled out a little, away from the other turns, so that you can stretch
the spring in order to put the bare ends of wires between the turns. Any
number of wires placed between these turns will be pinched and
electrically connected. The coil should be about 1/2 in. long and less
than 1/2 in. in diameter. You can make a coil by tightly wrapping stiff
iron wire around a pencil. The steel wire springs taken from old
window-shades are excellent for this purpose. They may be cut into
lengths with tinner's shears.

APPARATUS 43.

_61. Binding-Post._ Fig. 28. Two copper or tin strips fastened at one
end by a screw, the upper strip being bent a little at one end, make a
connector that is useful for some purposes, where you want to make and
break the connection frequently. The bare end of the wire which belongs
to the apparatus is fastened under the screw-head. The outside wire, or
wires, to be connected are pushed between the strips of metal. Another
way is to fasten the outside wire to a strip of metal about 1/2 in.
wide, and then push this between the strips shown in the figure. The
strips shown should be about 3/4 in. wide and 1-1/4 in. long.

[Illustration: Fig. 27.]

[Illustration: Fig. 28.]

[Illustration: Fig. 29.]

APPARATUS 44.

_62. Binding-Post._ Fig. 29. A combination made between App. 42 and 43
does we