Part 8 (1/2)

The wire may be wound on by hand, but a winder (App 93) will do much better and quicker work

APPARATUS 84

[Illustration: Fig 58]

[Illustration: Fig 59]

_113 Horseshoe Electro-Magnet_ Fig 58 Bend soft iron wires, and make a bundle of them If you wish to wind the wire around spools, the bundle cannot be very large It will be found best to make the bundle about 3/8 in in dia paper should be wrapped once or twice around the legs of the horseshoe, and the insulated wire, say 4 layers, can then be wound directly upon this (See -- 115 forconnection between the coils) It is a little troublesome to ire upon a horseshoe like this, and for App 85

Spools are handier, because each can be wound separately, and then be slipped in place The ends of the horseshoe should be filed s 59 An ordinary iron staple is useful as the core of a s 94, used as a telegraph sounder It takes so of the staple, so be sure to see -- 115 about the59 the half-hitches (-- 110) are not shown Coat the finished coils with paraffine

115 Method of Joining Coils Fig 60 If A and B represent the two cores of a horseshoe electro-net, the coils must be joined in such a manner that the current will pass around them in opposite directions, in order to make them unlike poles The current is supposed to pass around B, Fig 60, in the direction taken by clock hands, while it passes around A in an anti-clockwise direction The inside ends, -- 123, of the coils ether, or fastened under a screw-head In Fig

60 one coil is shown to be a continuation of the other

[Illustration: Fig 60]

APPARATUS 86

[Illustration: Fig 61]

[Illustration: Fig 62]

_116 Electro-Magnet_ Fig 61 Wind 6 layers of No 24 or 25 insulated copper wire around a 5/1661 shows one ht position, so that net studied Two nuts are used, the lower one being counter-sunk, so that the base will stand flat upon the table This bolt is shoithout washers (-- 119), and will do fairly well to show the action of electro-nets The ends of the wire should always be left 5 or 6 in long, and be led out to binding-posts The coilby coating it with paraffine The base may be of any desired size

APPARATUS 87

_117 Electro-Magnet Core_ Fig 62 This shows another ht position This is done without the use of two nuts A strip of tin, T, 1 in wide, is punched and slipped onto the 5/16 bolt before the nut is screwed on and the coil wound This is fastened to the base by screws, S Washers, W, are here shown (See -- 119 for washers)

APPARATUS 88

_118 Bolt Electro-Magnets_ are easy to iven, and they are, when finished, nets than any of the other forms described With proper batteries (App 3, 4, etc,) they can be used for a great variety of purposes, as will be seen There are many forms of bolts in the market, but the ordinary ”machine bolt,” 5/16 in in dia are used

119 Washers or coil ends are used on the bolt nets so that considerable wire can be wound on closely and evenly These are made out of thick pasteboard, which cuts smoother if it has been soaked in melted paraffine Unless you kno, you will find it a hard job to make the hole in the exact center of the washer The63

First place a spool (the end of which is 7/8 or 1 in in diameter) upon the table, and lay the pasteboard upon this Push a large round nail through the pasteboard into the hole in the spool The nail should be nearly as large as the hole Use the large nail as a handle, and with the shears cut around the edge of the spool end Cut the washer as round as possible, and be careful not to cut into the spool

The holes in the washers will be a little smaller than the 5/16 bolt

This will htly to the bolt when you force the 64 shows the bolt-core, with the washers in place If you cannot get a large nail, a lead-pencil, or sharpened doill do to force through the pasteboard

[Illustration: Fig 63]