. Annual report of the American Institute, of the City of New York. Science. 956 Transactions of the American Institute, possible, to the one it is required to test. These wires must then be connected together in a loop at the nearest available station beyond the fault, without ground connection. The resistance of the faulty wire, when perfect, must be ascertained. This may be taken from previous records, or it may be found by a test taken as follows'. 33. Connect the apparatus as in the diagram (Fig. 2, also frontis- piece), putting the loop in place of the resistance, to be measured as shown
. Annual report of the American Institute, of the City of New York. Science. 956 Transactions of the American Institute, possible, to the one it is required to test. These wires must then be connected together in a loop at the nearest available station beyond the fault, without ground connection. The resistance of the faulty wire, when perfect, must be ascertained. This may be taken from previous records, or it may be found by a test taken as follows'. 33. Connect the apparatus as in the diagram (Fig. 2, also frontis- piece), putting the loop in place of the resistance, to be measured as shown in the diagram ; that is, connect the good wire of the loop to III, and the bad wire to IV, and ascertain the resistance as directed (19-21). 34. Having ascertained the resistance of the loop, arrange the con- nections, as shown in the following diagram (Fig. 3).. Fig. 3. Kow turn the switch A to the right, and note the deflection; then turn it to the left, and unplug resistance until the same deflection is obtained; the resistance unplugged, deducted from the total resistance of the loop, and divided by 2, is the resistance of the bad wire between the apparatus and the fault. For example, suppose the resistance of the loop to be 1,000 ohms, and 1,000 ohms have been unplugged to balance the needle; the fault is 450 ohms from IV. Suppose the loop of 1,000 ohms is fifty miles in length, then by proportion 1,000 ohms : 50 miles :: 450 ohms : miles. 35. "When there is a fault on a line, and there is but one wire, it may be located by the following method: Ascertain, from former record, the normal resistance of the line; call this r. Also the resistance of the defective line, when grounded at the dis- tant end, as before directed (23); call this s. Also the resistance when open at the distant end, and call this t; and call the resistance of the wire between the fault and the testing station %; then x =s — -\/ ($* + tr) — (ts -^ rs). Please note that these images are e
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