Rheostats

Abstract

AN example of the great attention given to details nowadays in connection with apparatus for the laboratory and lecture-room use, and general experimental WQrk, is afforded by a 104 pp. list which a firm of electrical instrument makers (Messrs. Isen-thal and Co.) have sent us, devoted entirely to rheostats. It is not within the scope of the present article to indicate all the various patterns and modifications of these, but we may mention that we notice among the designs some convenient “twin” and “universal” patterns which enable a large range of resistance and accurate regulation to be obtained with apparatus of smaller dimensions than a simple rheostat would have for the same requirements. The catalogue contains a diagram of the “uhstrat”winding, designed to eliminate, so far as possible, capacity and safe induction. Two wires are wound in parallel in opposite directions and symmetrically, as shown in Fig. 1, which may be compared with the ordinary double winding shown in Fig. 2, and the Chaperon winding in Fig. 3.