Elements of telegraph operating, telegraphyInternational Textbook Company, 1901 |
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Vanlige uttrykk og setninger
adjusted alternating current ampere ampere-hours apparatus armature arrangement artificial line artificial-line battery binding posts branch office cable capacity cause charge closed coil condenser conductor connected contact points copper copper wire core cross-arms cuit current flowing curve dash diameter direct current direction distant office dots duplex dynamo earth electric electromagnet electromotive force equal fastened fuse ground G ground plate hence inches inductance inserted instruments insulated internal resistance iron length lightning arrester line circuit line wire local batteries machine magnet main-line Morse negative neutral relay number of cells number of turns office set ohms operator ordinary paper polar relay pole changer position quadruplex set quadruplex system receiving repeating sounder reversed rheostat row of disks screw self-induction sending shown in Fig side signals spring jack station strength switchboard T. G. Vol tape telegraph telephone terminals tion transmitter vibration volts wedge Western Union Wheatstone words wound zinc
Populære avsnitt
Side 70 - F., must not exceed the quotient arising from dividing the constant number 4,800 by the weight of the wire, in pounds per mile. The coefficient .003 will be allowed for each degree Fahrenheit in reducing to standard temperature.
Side 20 - F1G. 64. in two lines corresponding to the two directions of the current. Above the tape two brushes c and d are fixed, one connected to the positive pole and the other to the negative pole of the battery. The return wire or ground is connected to a point at the middle of the battery. Now, if in consequence of the perforations of the paper, either one of the two brushes comes into contact with the metal roller, either a positive or negative current flows through the roller to the line and thence...
Side 122 - The plugs are separated from each other by about ^ inch, the space c between them being only partially filled with a mixture of nickel and silver filings of uniform size and very clean and dry. Researches that have been made for a practical coherer have shown that the filings on electrodes should be made of a metal slightly oxidizable. The filings should be rather loose and in such a condition that when the tube is tapped, the filings may be seen to move. The filings should be rather coarse, such...
Side 114 - Suppose two fairly clean pieces of metal in light contact — say two pieces of iron — connected to a single voltaic cell ; a film of what may be called oxide intervenes between the surfaces, so that only an insignificant current is allowed to pass, because a volt or two is insufficient to break down the insulating film, except perhaps at one or two atoms.* If the film is not permitted to conduct at all, it is not very sensitive ; the most sensitive condition is attained when an infinitesimal current...
Side 85 - Beaume" hydrometer scale, there is too little sulphate of zinc; when it is 30° or over, there is too much in solution, and it must be diluted. When the zincs become coated so as to interfere with the proper action of the battery, they must be taken out, scraped clean, and washed. A gravity cell can be maintained in excellent condition by keeping it on a closed circuit about 60 per cent, of the time. If kept on open circuit too long a time the solutions mix and the cell is not ready for immediate...
Side 34 - The guy stubs should conform to the same specifications as the poles regarding quality of wood, and are usually made from the parts of poles too crooked to be used as poles. For ordinary purposes, a guy stub should be not less than 8 inches in diameter at the small end, and its length from 7 to 10 feet.
Side 12 - ... decrease in the current tends to induce a current in the same direction, self-induction may be said to be that property of a circuit that tends to prevent any change in the strength of a current flowing in it. Selfinduction has, therefore, been defined as the "inherent quality of an electric current that tends to impede the introduction, variation, or extinction of an electric current passing through an electric circuit.