Returning again to Fig. 39, we have the opening J, where the carriers are discharged, closed by a sluice-gate. This gate is opened and closed by a piston moving in a cylinder, _h_, shown in Fig. 38. A piston slide-valve, _i_, similar in all respects to the valve on the cylinder O, controls the movement of the piston in this cylinder and the sluice-gate to which it is attached. The slide-valve is moved in one direction, that opens the sluice-gate, by an electro-magnet in the circuit of the wires _a_ and _b_, Fig. 40. When the electric circuit made by these wires is closed by a disk on the front end of a carrier, short-circuiting the two needles, the valve is moved by the electro-magnet in the circuit, and the sluice-gate is opened. As the wheel, including the receiving tube and carrier, revolves, a lug, _j_, Fig. 38, on the outside of the wheel comes in contact with the open sluice-gate and the wheel can rotate no farther. A blast of air through the valve L, Fig. 39, assisted by gravity, pushes the carrier out of the receiving tube, through the opening J and down the chute Q, on to the receiving table. Had the disk on the front end of the carrier been too small to span the distance between the two needles, the circuit would not have been closed, the sluice-gate would not have been opened, no obstruction would have been placed in the path of the lug _j_, on the wheel, and the wheel would have continued its rotation through ninety degrees until the receiving tube F came in line with the tube D. During the latter part of the rotation, a pin on the wheel engages a lever, _k_, Fig. 38, and turns a valve, _l_, Fig. 39, stopping the flow of air through the passage C, compelling it to take another route through the passage _m_, and the receiving tube F, taking with it the carrier into the tube D. When the carrier leaves the receiving tube and passes through either of the openings J or K, it engages one of the fingers, _n_ or _o_, that lie in its path. These fingers are connected by rods and levers to the valves on the rotating and sluice-gate cylinders. The ejected carrier pushes these fingers to one side, and after it has passed the fingers return, by the force of a spring, to their former position and move the valves, causing the sluice-gate to close and the wheel to rotate backward into its normal position ready to receive the next carrier. The connection between the fingers and the valves is similar to the mechanism on the open and closed receivers, so need not be described in detail here.