176 J- N. Carruthers 



discernible on the face of the tube. A fin fused on one side of the bottle seats in a slot 

 cut into the tube to provide direction fixation, and the bottle is held firmly in place 

 by means of rubber bands as illustrated. 



Six fathoms of water in the River Crouch afforded enough messenger travel for 

 two wire gauges to operate with the " messenger-passer " in between them. The 

 latter always functioned without fail. At the time of writing this the deep-sea tests 

 to check the showings (pendulum behaviour) of the wire-angle gauges in the manner 

 described, are in progress aboard the Royal Research Ship Discovery II. 



If it were desired to observe the slope magnitudes and directions of a thick trawling 

 cable leading all the way down to a trawl or dredge being dragged over the deep ocean 

 floor, it would not be possible to use jelly bottles for time reasons. Also, any messengers 

 for the use of which a devised method might call would necessarily have to be of rather 

 mammoth size^ — each one something like a yard of heavy iron tube split and hinged 

 to go on the cable. It is suggested that a simple " messenger-passer " after the style 

 of that described could be made " rough, long, and strong " with a thin tight metal 

 rod of water bottle wire diameter held a small distance off from it (but parallel to it), 

 strained between two short spurs projecting out at right angles respectively at top and 

 bottom. If such crude devices were fastened on to the cable at desired intervals in the 

 manner already described, a wire-angle gauge could be operated at the bottom of the 

 thin offset rod in each case. This could be done quite simply if, when a giant messenger 

 struck to break the short length of thick glass rod or small phial which would be 

 necessary in such case, a daughter messenger of ordinary weight and size were 

 released to run down the offset rod to trip the gauge quite harmlessly. 



OTHER POSSIBILITIES 



In spite of the wide variety of current-meters already in existence, there remains 

 a real need for one which could be used to make all-weather absolute observations of 

 near-bottom currents from anchored vessels. The numerous and very convenient 

 lightships are in mind. The problem has always been how to get acceptable records 

 from a lively ship, and the suitable use of jelly bottles suggests itself as offering escape 

 from the difficulties imposed by ship movement, because they would be self-damping 

 systems. 



If a length of Kelvin wire carrying a heavy terminal plummet were let down from a 

 lightship, it would be easy to stream tow-nets from it at any desired depths. The nets 

 could be made of very wide mesh fishing net near their mouths, and the rest of stramin. 

 If streamed on up-and-down bridles the rings would not rotate. In such case there 

 could be a horizontal diametric brass rod across each net mouth, and on it could be 

 hung a semi-circular swinging plate carrying a compass-containing jelly bottle suitably 

 mounted on its reverse. 



Using some such simple arrangement with limp connection to the suspension line, 

 absolute measurements of currents could, it is held, be acceptably made during quite 

 bad weather. Such a method is well worth trying because of the great opportunities 

 which exist for working from anchored vessels. The necessary calibrations would, 

 of course, have to be made against logship runs. When the compass-containing and 

 depth-ignoring rolling clinometer spoken of above becomes available with slope- 

 reading possible to one degree and compass always on an even keel, the possibilities 

 will be greatly enhanced. Then, the simple current-measuring instrument envisaged 



