File:The Street railway journal (1896) (14761336535).jpg

Identifier: streetrailwayjo121896newy (find matches)
Title: The Street railway journal
Year: 1884 (1880s)
Authors:
Subjects: Street-railroads Electric railroads Transportation
Publisher: New York : McGraw Pub. Co.
Contributing Library: Smithsonian Libraries
Digitizing Sponsor: Smithsonian Libraries

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3, 4, 5, stations 500ft. apart, grounds were made by driving large iron barsdeep into the earth. The voltages employed were vari-ously from 60 to 150 volts direct current and alternatingcurrent from a small induction coil. The results werenearly coincident in all the sets of experiments and showedthe following curious state of affairs: Stations. Res. ohms. A . : B 92.4 Ground plates alone. A . . B 121.o Well plates alone. A . . B 66.8 Well and ground plates both. A . . I 201.6 A . . 2 374.0 A . . 3 92. A . . 4 506.3 A . . ,s 180.0 The resistance is evidently not a function of the distancenor of anything else that is at all obvious. The onlyfeature that is what might be expected, is the tolerablyregular effect of putting both sets of earth plates in parallelas exhibited in the first three lines of the table. The re-sistances at the intermediate stations show how hopelessit is to predicate anything of earth resistance except that Vol. Xn. No. 4.) ! STREET RAILWAY JOURNAL. (April, 1896.
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SKELETON OF AN EIGHTEEN FOOT CLOSED CAR, WITH NAMES OF PARTS. i 11t/ ) .( i April, 1896.) STREET RAILWAY JOURNAL. 231 it is too higli to be of any practical use save for trivialcurrents such as are employed in telegraphy. These experiments are in keeping with many others,all tending to show that unless on a very small scale theearth is nearly useless as an electrical conductor. As aconductor in parallel with a pair of heavy and well bondedrails, the earth is hardly to be .seriously considered at all. Imagine the stations A and B, Fig. 22, to beconnected by a track consisting of a pair of sixtypound rails thoroughly connected and put inparallel with the circuit via the earth connec- ^tious. At be.st this has a resistance of 66.8ohms while that of the track should be at worstonly a few tenths of an ohm. Following theordinary law of derived circuits, it is clear that thecurrent returning via the earth is only a minutefraction of one per cent of the whole. If thetrack could be continuousl

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