238 Mr Sharpe, Liquid Motion from a Single Source, etc. 
The shape of the curve is given in Fig. 7. If OF be the perpen- 
dicular on the asymptote it can be shewn from (65) that OY is 
about j^th of the radius, so that the boundary strongly resembles 
a cone of semiangle 7t/3 with source at the vertex. It is interest- 
ing to notice that if we had such a conical boundary, we might see 
by only considering the inflow of the liquid at 0 and its outflow 
at infinity, that equation (63) would hold, and the same would be 
the case for a boundary having a general likeness to BAD (Fig. 7), 
but this would give us only the approximate velocity of the liquid 
at infinity. The above investigation however gives us the whole 
of the fluid motion from the source outwards. We can also get an 
infinite number of boundaries having a given reflective power — 
say for instance defined by equation (63). 
