It not unfrequently occurs that pulleys, the driver and driven, must be placed'very near together, necessitating a short belt, which, whether for efficiency or durability, is not economical, as the belt must be kept very tight. Especially is this arrangement objectionable when the driver is very much larger than the driven. We give an illustration of a device for obviating this annoyance, which we see in Engineering applied to a portable centrifugal pump. The driver, A, revolves in the direction of the arrow, carrying a belt to the driven, B, and between the two is interposed a friction wheel, C, bearing equally on the faces of both pulleys. The face of this intermediate is hollowed so that it bears on the outer edges of the pulleys. Its effect is to relieve the great strain on the shaft of B.