is amenable to remote application so shielding requirements would be minimal. 
The necessary development will be in manipulating a gun of optimum design 
for cutting into competent rock, developing methods of quenching to optimize 
spalling, and a machine to hold and move the gun. A suitable model of a gun 
is believed to have been designed by Westinghouse. 
Fully developed, the electron beam cutter for rock is believed to be 
one of two methods suitable for use in the subbottom excavation. The other 
method, which appears feasible in both the one-atmosphere situation of the 
subbottom cavity and the full pressure of the ocean, is the high-velocity water 
jet (Figure 64) under development by the Exotech Corporation of Rockville, 
Maryland, and under research by others (Maurer and Heilhecker, 1969). The 
later work proves the feasibility of erroding very hard rock if sufficiently high 
velocity (high water-nozzle pressure, usually) can be achieved. For deep-ocean 
rock excavation, the method appears to be especially advantageous in that the 
power is conveniently and probably preferentially transmitted as high-pressure 
hydraulic power in a hose. It can then be locally intensified by use of variable- 
area piston pumps (one large piston at the lower pressure directly connected 
with a small piston on the same reciprocating rod) with pressure intensification 
at approximately the ratio of the piston areas. 
Two important methods of jet formation are recognized. First, the 
straight jet with a velocity V = (2gh)/2, a well known hydraulic relationship. 
This type of jet has been effective in drilling rock with pressure heads of 
8,000 to 16,000 psi (Maurer and Heilhecker, 1969). Presumably even more 
effective are single-shot machines using a formed capsule of gelatin. |n jets 
of this type, a conical impactor reacts kinetically to accelerate the shaped 
gelatin in what might be called a ‘shaped jet,’’ which is free standing and 
not subject to the usual limitations of hydraulics, including wall friction. 
Stagnation pressures are reportedly achievable of about a million pounds 
per square inch. Losses in the velocity of the jet can be established by 
equating the momentum of the impacting conical ram and the initially 
stationary cylinder of gelatin, which acts as a liquid at high flow rates. In 
its present state of development in the United States, the system is limited 
by the single-shot aspect and the requirement for a shaped annular cylinder 
of gelatin which must be replaced after each shot. A recent disclosure (Beck, 
1970) of a method of using water and providing for rapid replenishment of 
the charge (to make the device rapidly repeating) needs demonstration, but 
is entirely practicable theoretically (Figure 65). Incorporated into a system 
such as that shown schematically in Figure 64, it should be possible to work 
in the vertical position in the deep ocean, with a charge of air at the local 
sea pressure In the pressure head. To achieve the centrifugal configuration 
of the working charge of water, it is clearly necessary to have two liquids 
85 
