Part 18 (1/2)

289 Copper Sheet-copper can be purchased at a tinsmith's or at a hardware store Electricians usually have a thin variety of copper called brush copper, which -posts, etc You can cut this thin copper with an ordinary pair of shears

290 Iron For thin sheet-iron, nothing is better than sheet-tin (See tin) Hoop iron is thicker than tin, and ood yokes, etc In netic substance is needed

Annealed iron wire is extremely soft (See text-book for experiments with steel and iron)

291 Steel Old files, watch-springs, clock-springs, corset-steels, knitting-needles, harness-needles, hack-saw blades, sewing-needles, etc, are generally ood quality of steel

292 Zinc, in the sheet forht at a hardware store For a few cents you can get quite a large piece Get the thick pieces for heavy battery-plates of an electrician You do not need anything that is thicker than 1/8 in The zinc rods are usually aht at a plumber's, tinsmith's, or hardware store

You e cell

294 Nails Wire nails are best for light work Get an assort up to 1-1/2 in

295 Screws It is better to use brass screws around electrical apparatus For the s-posts, etc, use 5/8 No 5

Another handy size is No 7, fro The round-headed screws are best, unless you want to countersink them

296 Tin This is really thin sheet-iron, covered with tin Save up tomato-cans, cracker-boxes, condensed-ood as sheet-tin, as the pieces are large and clean You can re them in the kitchen fire

Knock out the bottoets soft Clean the tin with sand-paper

297 Carbons You can get carbon rods or plates at an electrician's If you have arc electric lights in your city, you will be able to pick up carbons; these, however, generally have a coating of copper, which must be eaten off with dilute nitric acid This is a bother You will find it cheaper to buy the 1/2 in rods that are 12 in long, and uncoated

298 Shellac Your ill beshellac upon it after you have thoroughly sand-papered it You can get it, all prepared, at a paint store Wood-alcohol is used to thin it if it gets too thick Keep it in a wide-mouth bottle Paint it on quickly and evenly with a brush, and do not go over it again when it is partly dry

Wait until it is thoroughly hard before putting on a second coat It should be fairly thin to spread well Clean your brush in wood-alcohol before putting it away, and keep the shellac bottle tightly corked A small tin can or a teacup is best to hold the shellac when using it

THINGS A BOY SHOULD KNOW ABOUT ELECTRICITY

By THOMAS M ST JOHN, Met E

The book contains 180 pages, and 260 illustrations; it measures 5 7-1/2 in, and is bound in cloth

Seventh Edition Price, postpaid, 100

CONTENTS: Chapter I About Frictional Electricity--II About Magnets and Magnetism--III How Electricity is Generated by the Voltaic Cell--IV Various Voltaic Cells--V About Push-buttons, Switches and Binding-Posts--VI Units and Apparatus for Electrical Measurements--VII Chemical Effects of the Electric Current--VIII How Electroplating and Electrotyping are Done--IX

The Storage Battery and How it Works--X How Electricity is Generated by Heat--XI Magnetic Effects of the Electric Current--XII How Electricity is Generated by Induction--XIII

How the Induction Coil Works--XIV The Electric Telegraph, and How it Sends Messages--XV The Electric Bell and Some of its Uses--XVI The Telephone, and How it Transmits Speech--XVII How Electricity is Generated by Dynamos--XVIII How the Electric Current is Transformed--XIX How Electric Currents are Distributed for Use--XX How Heat is Produced by the Electric Current--XXI

How Light is Produced by the Incandescent Laht is Produced by the Arc Lamp--XXIII X-Rays, and How the Bones of the Huraphed--XXIV The Electric Motor and How it Does Work--XXV Electric Cars, Boats and Automobiles--XXVI A Word About Central Stations--XXVII Miscellaneous Uses of Electricity

This book explains, in sis about electricity; things in which the As he wants to know; things he should know