Wireless Telegraphy and Telephony

______________________ LIST OF ILLUSTRATIONS PAGE Fig. I .—Throw a stone into a pool of water and little waves will radiate from the spot where the stone struck . . I Fig. 2 .—A Leyden jar is a glass jar lined inside and outside with tinfoil for about two-thirds of its height ... 3 Fig. 3 .—A static machine connected to a Leyden jar . . 4 Fig. 4 .—A Leyden jar discharging through a coil of wire . 5 Fig. 5 .—Curved line representing an oscillatory discharge of a Leyden jar_____________________________________ 5 Fig. 6 .—Navy type of Leyden jars_______________________ 6 Fig. 7 .—The simplest practical transmitter .... 7 Fig. 8 .—A cross-section of the aerial and atmosphere . . 9 Fig. g—Under the same conditions, but viewed from above . 9 Fig. 10 .—A simple receiving arrangement .... 10 Fig. 11 .—An amateur aerial and station___________________*3 Fig. 12 .—The Army wireless station at Fort Gibbons . . 14 Fig. 13 .—Lightning discharge near Montclair, N. J. . 15 Fig. 14 .—Photo of double lightning discharge passing to earth near the First Orange Mountain, Montclair, N. J. . • *7 Fig. 15 .—Vertical aerials of the grid, fan and inverted pyra- mid types_________________________________________*8 Fig. 16 .—A diagram showing pyramid aerial .... 19 Fig. 17 .—A diagram illustrating the directive action of a flat- top aerial_________________________________________ Fig. 18 .—Aerials of the “V” and inverted “L” types Fig. 19 .—A diagram showing the arrangement of a “ F ’ aerial Fig. 20 .—Flat top aerials of the inverted “U” and “T” types Fig. 21 .—Umbrella aerial________________________________ Fig. 22 .—An amateur aerial (flat top)__________________23 Fig. 23 .—Diagram showing the difference between loop and straightaway aerials...............................24 Fig. 24 .—Showing how wires are arranged and insulated . 25 Fig. 25 .—Aerial insulator_______________________________25 xi