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INVENTIONS OF NIKOLA TESLA.

between the disc and the contact ring on the periphery, as illus-trated in Fig. 296.

A Forbes dynamo may, for instance, be excited in such a man-ner. In the experience of the writer it has been found that in-stead of taking the current from two such discs by slidingcontacts, as usual, a flexible conducting belt may be employedto advantage. The discs are in such case provided with largeflanges, affording a very great contact surface. The belt shouldbe made to bear on the flanges with spring pressure to take upthe expansion. Several machines with belt contact were con-structed by the writer two years ago, and worked satisfactorily;but for want of time the work in that direction has been tempor-arily suspended. A number of features pointed out above havealso been used by the writer in connection with some types ofalternating current motors.