. The railroad and engineering journal . ed are an electrical treadle (figs, i to 6) and an elec-tric slot (figs. 7 to 9). Fig. 10 shows the general arrange-ment of interlocking the block instruments with the pointand signal levers when such interlocking is adopted, andfig. 11 is a diagram of an ordinary through station andshows the general arrangement of signals, block instru-ments, etc. Treadles of all kinds have been tried before ;those acting mechanically soon get put out of order bythe heavy and constant shocks to which they are subject,while the electrical ones suffer from the displaceme
. The railroad and engineering journal . ed are an electrical treadle (figs, i to 6) and an elec-tric slot (figs. 7 to 9). Fig. 10 shows the general arrange-ment of interlocking the block instruments with the pointand signal levers when such interlocking is adopted, andfig. 11 is a diagram of an ordinary through station andshows the general arrangement of signals, block instru-ments, etc. Treadles of all kinds have been tried before ;those acting mechanically soon get put out of order bythe heavy and constant shocks to which they are subject,while the electrical ones suffer from the displacement of Vol. LXI, No. 9.] ENGINEERING JOURNAL. A12 the line, which either brings the contacts into constantconnection, or removes them so far apart that they failto meet when required. The problem of their construc-tion does not appear particularly dillicult at first sight,but the long list of failures which liave talcen place isevidence that the traffic imposes conditions which cannotbe easily met. Messrs. Saxby & Farmer have avoided. all the inconveniences resulting from changes of level bythe use of a fluid medium—mercury—as one of the electricconductors. This is contained in a rectangular box, andover the center of its surface the contact point is , if the be inclined to one end or the other, thecenter of the fluid surface always keeps at the same height,and stands at the same distance from the terminal. If the box be shaken, however, the fluid surface breaks intowaves, and the crest of one of these breaking against thecontact wire (fig. 6) completes the circuit and sends acurrent to the cabin. In the longitudinal section of theI)0X (fig. 5) there is shown a diaphragm with a space aboveand below it for the circulation of air and mercury. Thisdiaphragm is interposed because without it there is alwaysa hollow in the rippled surface of the mercury in tlie cen-ter of the box, and no matter how violent the vibrations,the mercury will never meet the wire and comp
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Keywords: ., bookcentury1800, bookdecade1880, booksubjectrailroa, bookyear1887
