746 



DR E. M. WEDDERBURN AND MR A. W. YOUNG ON 



dispense with directing vanes altogether by having three sets of spring propellers 

 set in three planes in directions at right angles to one another. The movable parts 

 of such an instrument could be made quite light and of small momentum. The 

 whole instrument would be compact and easy to handle, and probably more reliable 

 in its action than an instrument depending on the movement of heavy vanes. 



The thermograph and the current-meter each weighed about 50 lbs. in water. 

 Owing to their weight and size it was not practicable to use them from a single 

 rowing boat. A raft was constructed by mooring two boats side by side, but four 

 feet apart, and fixing over them a framework from which the instruments could 



100 



80 



60 



40 



20 





































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•Y 





























-^- 

















n 



/ ^ 





' 





r 



r t 



', 7 



6 



9 



9 cm. 



Fig. 3. — Calibration of Current- Meter. 



For ease in handling, 



both the large instruments were balanced 



measuring the depths to which the instruments 



be suspended 



by counterpoise weights. For 



were lowered measuring pulleys of ^-metre circumference, made by the late Mr A. 



Frazer, were used. 



A general idea of the whole arrangement may be gathered from the photographs 

 forming fig. 4, the upper of which shows the thermograph and current-meter 

 in position for lowering to any desired depth. 



Six ordinary reversing deep-sea thermometers were used, two of which were lent 

 by the late Sir John Murray, K.C.B., and one by Dr W. S. Bruce. All the instru- 

 ments were carefully compared with a thermometer for which a Kew certificate had 

 been obtained, and corrections were applied. The observations were made to the 

 nearest twentieth of a degree C. 



