Stephen A. Greene and Israel Greene, of Westerly, R. I., have taken measures to secure a patent for the above. In order to preserve a uniform ''let off," it is necessary that the movement of the yarn beam upon its axis increase in the same ratio with the decrease of its operative diameter, caused by the decrease in the quantity of yarn. For this purpose the above invention consists in communicating the necessary intermittent motion to the yarn beam by a train of mechanism which is actuated by a constantly revolving cam or eccentric, operating on a lever whose position is so controlled by a shoe or bearing piece, which always presses against the yarn on the beam, that when the latter is full the action of the cam on the lever is such as to move it slightly, but that as the quantity decreases, the action of the cam gives a proper increase to the motion of the lever, and consequently to the motion imparted by it to the beam.