Part 7 (1/2)

APPARATUS 73

_99 Yoke_ Fig 47 The yoke, Y, is a part of a carriage This can be bought at a blacksmith's The holes are already in, but it nets will fit down fir 47]

APPARATUS 74

_100 Tin Arether 5 or 6 thicknesses of tin Different forraph sounders; these should have a hole punched at the center; through this is put a screw The length of the arnets are placed apart; they should be about 3/4 in wide

APPARATUS 75

_101 Nail Arh a piece of wood, A, will serve as a very simple armature To make it a little heavier, if necessary, a piece of annealed iron wire, W, may be wound around N Care should be taken to have the two parts fairly alike in size and weight

[Illustration: Fig 48]

APPARATUS 76

_102 Wire Arood arhtened (See App 28) before binding theether with thread or paraffine, until they are in place, as, for exa 49 The bundle of wires should fit snugly into the hole ether at each end ire

[Illustration: Fig 49]

APPARATUS 77

_103 Tre 50 Armatures to be used upon electric bells, automatic current interrupters, buzzers, etc,armatures They ives it the spring, should be about 5/8 in wide Its length will depend upon the particular apparatus to be50 for dimensions The part N projects beyond L Thisscrew, or to fasten a hammer on for an electric bell The part, L, should have about 4 layers of tin on each side of F, and it should pinch F tightly

[Illustration: Fig 50]

APPARATUS 78

_104 Tre 51 When very rapidarht and quick-acting armature can be made of sheet-tin The exact dimensions will depend upon the use to be uide Cut the part, B, E, out of thin tin The covers and bottoms of tin cans are thinner than their bodies The narrow part, B, should be about 1/4 in wide and 2 in long for a sh E is a screhich holds it firmly to a wooden piece, D, about 3/4 in square The part, E, can be er than its width, so that two screws can be used; this will keep A fro 51]

APPARATUS 79

[Illustration: Fig 52]

_105 To File Thin Metal Strips_ Fig 52 When sheet-metal is punched by the e or bur is made on the underside around the hole If this bur be hammered to flatten it, the hole is distorted and made smaller It is better to file the bur down, at least part way It is not convenient to file a piece of thin metal when it is held in a vise It is better to use either acan be quickly and easily done Y is the yoke to be filed It is well to place a piece of metal, I, between the table and the end of the screw

APPARATUS 80