. Monde électrique. indicateur de mesure est montée sur un arbre de l'acier, les points dont sont durcis et charge dans le saphir rubis, practicallyeliminating toutes frictions ou un retard. Comment parfaitement c'est accom-plished peut être jugé du fait qu'un changement de vitesse de un cinquième de I p. 100, s'affiche sur le cadran. Depuis le cadran et très shaftare la lumière, la force des joyaux et pivot est grand en com-paraison au poids, et l'expérience a montré qu'ils willstand indéfiniment le service régulier susceptible de tenir compte dans un ordi-nary machine shop. Fig. 3 montre une coupe d'un multimètre complet, f

• Contributeur: The Reading Room / Alamy Banque D'Images
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. Electrical world. indicating dial is mounted on a steel shaft, the points ofwhich are hardened and supported in sapphire jewels, practicallyeliminating all friction or retardation. How perfectly this is accom-plished can be judged from the fact that a change in speed of one-fifth of I per cent, is shown on the dial. Since the dial and shaftare very light, the strength of the jewels and pivot is great in com-parison to the weight, and experience has shown that they willstand indefinitely the regular service likely to be given in any ordi-nary machine shop. Fig. 3 shows a cut-meter complete, full size. The instrumentis sufficiently small and light, so that it can be carried in the pocketwithout inconvenience. It presents a very handsome appearance, being substantially constructed of brass and nickel-plated. Thehandle is turned from a hard tropical wood and is highly polished. The material of the ball bearings is a superior quality of softsteel, which is first finished to shape and then case-hardened. Each. FIG. 2.—THE CUT-METER IX USE. piece is ground on a specially-constructed machine, so that every partmay be true and in perfect alignment. After being ground, eachpart is carefully tested, and imperfect or soft pieces discarded. Fig. I shows the details of bearings. In a test several of thebearings were run at a speed of 15, 000 r.p.m. for a sufficient length oftime to equal several years actual work on the instrument; at theend of this crucial test, the bearings were found to be in as perfectcondition as before. The magnet is practically permanent under all conditions. Theair-gap is only about 1/32 of an inch, or about one-half of i per cent, of the entire length of the magnet. This narrow air-gap effectuallyprevents the instrument from being influenced by outside magnetic May 7, 1904. ELECTRICAL WORLD and ENGINEER. 887 forces, and the strongest field does not affect its accuracy in theslightest degree. The steel used is of a special quality and is made toorder. Th

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