Part 4 (2/2)

APPARATUS 44

_62 Binding-Post_ Fig 29 A combination made between App 42 and 43 does well Fasten a metal strip, 3/4 in 1-1/4 in, to the apparatus by means of a screw The apparatus wire should be fastened under the screw-head A short length of spring ht part of the strip, as shown Into this you can quickly fasten the outside wires

APPARATUS 45

_63 Binding-Post_ Fig 30 This -post for home-made apparatus It consists of a screw-eye, preferably of brass The circle or eye should be about 3/8 or 1/2 in in diameter The thread on such a screw-eye will be about 1/2 in long Two copper burs are used to pinch the wires

APPARATUS 46

_64 Binding-Post_ Fig 31 This consists of a screw, screw-eye, bur and a metal strip, 3/4 1-1/4 in The apparatus wire should be fastened under the screw-head Any outside wires which are to be joined to the apparatus should be cla the screw-eye A s in the screw-eye

(See App 25) Do not turn the screw-eye too hard, or you will spoil the thread30]

[Illustration: Fig 31]

[Illustration: Fig 32]

APPARATUS 47

_65 Binding-Post_ Fig 32 The size of the bolt used in this for-post will depend soeneral, a 3/4 or 7/8 in base should be used where screws or screw-eyes are necessary With this kind (Fig 32) a thin base can be used The head is shown counter-sunk into the bottom of the base

This is not necessary, provided at least 3 heads are placed far enough apart to fors for the apparatus to stand on Strips of wood may be nailed upon the underside of the base to s The wires should be pinched between the nut and the copper bur shown If the bolt is too large for a bur, an iron washer may be used A washer may be made of tin, or two nuts33 This is a suggestion for a combination of App 44 and 47 It is useful in school apparatus Wires ht, under the nut, and a spring, as in App 44, may be slipped on the metal strip at the left, which is held under the head of the bolt

[Illustration: Fig 33]

APPARATUS 49

_67 Mercury Connector_ A cup of mercury may be used as a connector

Make a small hole about 1/4 in in diameter and depth, in a piece of wood, and place 2 or 3 drops of mercury in this The ends of wires dipped in this will be electrically connected

APPARATUS 50

[Illustration: Fig 34]

_68 Connector_ Fig 34 This shoire may be fastened to one end of a short strip of tin At the other end of the strip a slot is cut This may straddle the body of a screw, or when left plain may be used to slip between the two metal strips shown in App 43