6'8 REPORT OF COMMISSIONER OF FISH AND FISHERIES. [66] 



firmly on their seats by the resistance of the water, and each propeller 

 begins to screw down along its shaft under the same influence. When 

 the upper thread inshle the hub of the propeller clears the lower cor- 

 responding thread on the shaft the propeller uncouples, and drops upon 

 the screw cap, which it clutches. The screw cap is then carried down 

 until it comes in contact with the upper valve, from which position it 

 cannot be removed by the action of the water or of the propeller. 

 Both valves being thus locked, stoppages may be made thereafter dur- 

 ing the ascent without risking the identity of the inclosed specimen of 

 water. 



"The distance through which the cup must pass, in order that the 

 propeller may traverse, the shaft and lock the valves, may be varied 

 by altering the pitch of the propeller. As shown in the drawing the 

 propeller would probably not perform its work short of 50 fathoms. I 

 settled on about 25 fathoms as the distance most convenient. With this 

 distance it would not be prudent to require the uppermost cup to 

 bring a specimen from nearer the surface than 50 fathoms. If the 

 propellers were arranged to lock the valve in an ascent of about 25 

 fathoms, and the uppermost cup were lowered only to a depth of 10 

 fathoms, for instance, obviously, when that cup had arrived at the 

 height of the vessel's deck, the submerged cups, having passed through 

 a distance of only about 12 fathoms, would not have become locked. 

 Each cup, as soon as discharged, should be thoroughly rinsed in fresh 

 water." 



We have found these bottles to work satisfactorily for the purpose 

 of collecting water specimens for specific gravity determiua f ons ; but 

 they will not retain the gases, and are therefore not available for col- 

 lecting specimens for chemical analysis. 



Experience has taught us that it is advisable to reset the valves 

 whenever the bottles are to be used, as their adjustment is liable to be 

 impaired in releasing the screw cap from contact with the upper valve. 

 Although Sigsbee states in the remarks quoted that the upper valve 

 seat is detachable for purposes of cleaning, we find in practice that the 

 accumulation of verdigris on the screw threads makes its safe removal 

 impracticable. The valves and valve seats can be readily cleaned, 

 however, without detaching the upper valve seat. 



IMPROVED WATER BOTTLE. 



The improved water bottle, Plates XXXV, XXXVI, and XXXVII, 

 is designed to bring up a specimen of water from any desired depth, re- 

 taining the free gases for the purpose.of analysis. The valves close 

 mechanically and cannot be opened again except by hand , therefore it 

 may, like the Sigsbee water specimen cup, be used in series, either with 

 others of the same kind or with any instrument that can be used in 

 series. 



