594 FISHERIES OF THE UNITED STATES. [82] 



bee's Deep- Sea Sounding and Dredging, published by the United States 

 Coast and Geodetic Survey, in 1880 and in 1882, pages 90 to 98. The 

 following description and explanation will give a general idea of the 

 invention : 



Parts of the cup. — A cylinder ; a lower valve-seat which screws to the 

 cylinder by a right-hand thread ; a detachable upper valve-seat, de- 

 tachable to allow the removal of the upper seat for cleaning ; upper 

 and lower poppet valves connected by an adjustable stem ; a frame 

 fastened to the cylinder with a left-hand thread, inclosing the upper 

 valve-seat ; a shaft with two sets of external screw threads ; a pro- 

 peller composed of two bent blades ; a hub having an internal screw 

 thread, a removable cup, and two beveled lugs ; a screw cap or follower 

 with milled head, two beveled slots, and internal screw threads; a re- 

 movable sleeve and locking pin ; a binding clamp, composed of a single 

 wire lever, a pivot screw, and two contact lugs. The delicate working 

 parts are of German silver, which does not corrode in sea water. All 

 delicate screw threads are inclosed, as a protection against fouling by 

 grit, &c. 



Working. — The cup comes to the surface filled with water, the screw- 

 follower down upon the upper valve, and the propeller resting upon the 

 follower. To remove the water first screw up the propeller until it takes 

 on the thread of the shaft ; then screw up the follower until it uncouples 

 from its thread. The valves may then be raised and the water dis- 

 charged. 



After the follower has been uncoupled the cup is automatic in its 

 working, and it is only necessary to clamp it on the line with the spring 

 binding clamp. Before paying out, the propeller may be screwed up to 

 its fullest extent, but this is not necessary. As the cup descends the 

 resistance of the water raises the valves, and also screws up the pro- 

 peller until the lower thread in the hub clears the upper thread on the 

 shaft, when the propeller uncouples and revolves freely on the shaft, 

 where it is guided at top and bottom, which prevents chafe on the 

 thread. Should a stoppage then be made to fasten on another cup, 

 the propeller will not screw down by the rolling or pitching of the 

 vessel. 



It will be noticed that the blades are bent on their upper edges. 

 With the blades thus bent, and the propeller made very light,* it has 

 been found, experimentally, that by rising and falling equal distances 

 through the water the propeller will screw up instead of down. Unless 

 the propeller blades were bent, it is evident that the propeller would 

 gradually screw down by a rising and falling motion, since its weight 

 would aid in screwing down and resist in screwing up; but, even thus, 

 experiments have shown that for an alternating motion through the 

 water, continued for a longer time than any probable stoppage, the 

 propeller would screw down only about a quarter of an inch, which is 

 * The propeller might he made of aluminum, 



