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XVIII. 



ON THE INVESTIGATION OF THE DEEP-SEA DEPOSITS. 

 By J. JOLY, D.Sc, E.E.S. 



(Pl.ATES XIX, XX.) 

 [Read Jandaey 27. Published April 27, 1914.] 



In 1897 I communicated to the Royal Dublin Society a suggested method 

 of boring into such rocks as might be exposed on the sea-floor. The boring- 

 machine then described involved a motor to drive the drill and an insulated 

 wire from the surface. This machine I subsequently improved, but the 

 features just referi-ed to still remained as essential. 



There are difficulties and mucli expense involved in transmitting electric 

 power from the surface to the bottom at great depths. To develop power 

 below from storage cells or wound-up springs presents even greater 

 difficulties. These considerations have prevented me from hitherto em- 

 barking on the construction of any machine intended for the purpose of 

 submarine exploration. 



Recently, however, it occurred to me that the pressure of the water 

 prevailing at great depths might itself be utilized to provide the necessary 

 power in situ. The principle is simple. Suppose an empty vessel, of 

 sufficient strength to resist the pressure, lowered to the bottom. This 

 provides a receptacle into which the working substance — that is the water 

 — may be discharged after it has done work in a hydraulic engine. This 

 engine may be of the ordinary reciprocating type with the usual directions 

 of the pressure reversed and acting from without inwards. Or the motor 

 may be of the Pelton-wheel form ; the wheel being protected from the 

 pressure, and water directed from without upon it, the spent water finding 

 its way to the receptacle. 



The dynamical principles are easily stated. We may trace back the 

 work to the sinking of the receptacle under the influence of gravity — a 

 general rise in the level of the ocean occurring in consequence. In this 

 operation we do no work. We, in fact, borrow the work at the expense 

 of the conditions of gravitational potential obtaining. If we desire to recover 

 the receptacle, however, we must pay back what we have borrowed. It is 



