Electrical news and engineering . ton thousandrespectively. The scale is 110 inms. in length divided, by calibration,into 50 nearly equal parts, and the position of the indexcan be read quite easily to less than one quarter of a divi-sion. The reading can be noted within four ..r hve seconds, and a complete test will not usually occupy more than oneminute from start to finish. The readings are very nearlyindependent of the strength of the testing current, whichmay vary within wide limits without causing any appreci-able error. Compensation is made for temperature andhence the scale reading giv
Electrical news and engineering . ton thousandrespectively. The scale is 110 inms. in length divided, by calibration,into 50 nearly equal parts, and the position of the indexcan be read quite easily to less than one quarter of a divi-sion. The reading can be noted within four ..r hve seconds, and a complete test will not usually occupy more than oneminute from start to finish. The readings are very nearlyindependent of the strength of the testing current, whichmay vary within wide limits without causing any appreci-able error. Compensation is made for temperature andhence the scale reading gives the actual value which thetest resistance has at the time the test is made, no matterwhat the temperature of instrument itself may be. The ductor is intended to give the manufacturer all theinformation he needs about the resistance of the conduct-ing parts of the things he makes, and give the plant user thesame information as to the things he uses. A defective fuse,a bad contact, a faulty coupling or some other defective part. Kvershe< Dmtor for Small Hcsistances. may fail, and the failure of one link in the chain may in-volve the breakdown of the whole system. Apart from de-fective insulation the first sign of impending failure in anypart of a circuit is an abnormal change in its conductor re-sistance; it is the function of the ductor to detect the changelong before the danger point is reached. For example, bythe time a contact becomes overheated, breakdown is im-minent; the ductor detects the gradual deterioration of acontact long before any abnormal rise of temperature isapparent. Ironite Drop Cord The Central Electric & School Supply Company. To-ronto, announce that they have recently added the well-known Ironite drop wire to their stock of electrical sup-plies. Among the claims made for this wire are the fol-lowing; 11 lKl^ iiniplo conductivity; wont draw down or io6 THE ELECTRICA NEWS break because of heat or snap under the weight of snow andsleet, yet is stronge
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