.......................................... Fig. 88.—Graphic Representation of a Direct and an Alternating Current. .......................................................... Fig. 89.—Staples and Wooden Cleat used for running Low Voltage Wires. ............................................................ Fig. 90.—Porcelain Insulators to support Electric Light Wires. .... Fig. 91.—Glass Insulator Binding-Posts and Pin used to support Telegraph and Telephone wires. .................................... Fig. 92.—Types of Binding-Posts. .................................. Fig. 93.—Home-made Binding-Posts. ................................. Fig. 94.—Binding-Post removed from the Carbon of a Dry Cell. ...... Fig. 95.—Simple Switches. _A_, Single-Point Switch. _B_, Two-Point Switch. _C_, Three-Point Switch. _D_, Five-Point Switch. _E_, Lever with End Rolled up to form Handle. _F_, Lever with Handle made from part of a Spool. .................................................. Fig. 96.—Knife Switches. .......................................... Fig. 97.—Metal Parts for the Knife Switches. ...................... Fig. 98.—Simple Fuses. _A_, Fuse-Block with plain Wire Fuse. _D_, Fuse-Block with Mica Fuse in position. ............................ Fig. 99.—Lightning-Arrester and Ground-Wire Switch. ............... Fig. 100.—Home-made Lightning-Arrester. ........................... Fig. 101.—Lightning-Arrester for Telephone Wires. ................. Fig. 102.—_A_, Base, showing Slot. _B_ and _C_, Sides and Top of the Bobbin. _D_, Base and Bobbin in Position. ......................... Fig. 103.—Arrangement of the Needle and Pointer. .................. Fig. 104.—_A_, Bearings. _B_, How the Needle is mounted. .......... Fig. 105.—The Completed Meter. .................................... Fig. 106.—Details of the Bobbin. .................................. Fig. 107.—The Bobbin partly cut away so as to show the Bearing. Details of the Armature and Shaft. ................................ Fig. 108.—Completed Voltmeter. .................................... Fig. 109.—Circuits for Calibrating the Ammeter and Voltmeter. ..... Fig. 110.—Simple Compass Galvanoscope. ............................ Fig. 111.—Galvanoscope. ........................................... Fig. 112.—Astatic Galvanoscope. ................................... Fig. 113.—Astatic Needles. ........................................ Fig. 114.—Bobbin for Astatic Galvanometer. ........................ Fig. 115.—Completed Astatic Galvanometer. ......................... Fig. 116.—Wheatstone Bridge. ...................................... Fig. 117.—Knife-Contact. .......................................... Fig. 118.—Resistance-Coil. _A_ shows how the Wire is doubled and wound on the Spool. _B_ is the completed Coil. .................... Fig.