A small (35 cm x 15 cm x 20,5 cm) reversiblemachine for the transformation of mechanical energy into electrical energy when made to work as a dynamo and of electrical energy into mechanical energy when made to work as an electrical motor.

It is fixed to a wooden platform (58 x 21.5 cm) by means of two wooden blocks; the drave shaft is vertical and is attached to the platform by means of a support equipped with an adjusting screw and one transmission pulley at the top (working diameter 7 cm) and two at the bottom (working diameter 3.8 cm).It is the most significant evidence of Antonio Pacinotti's period in Cagliari as a professor of Experimental Physics at the Royal University (1873-1881). Inventoried only in 1887 (six years after his transfer to Pisa!), it was constructed by Pacinotti himself together with the machinist and assistant preparer of the Physics Laboratory, Giuseppe Dessì, between 1878 and 1880.Two others were built at the same time: one is now in Pisa in the Pacinotti Museum and the other is in the London Science Museum. ...continues