32G 
PEOFESSOR 0. EEYEOLES Am) MR. W. H. :\100RBY 
a small stuffing-box in the cap, to allow of a spindle for connecting the shaft witb the 
counter. 
These entailed very difficult and exceptional work, but were beautifully executed 
by Mr, Foster, in the Laboratory (fig. 9). 
However, the result was very doubtful, as the water flowing from the brake through 
the aperture in the stuffing-box not only raised the temperature of the shaft, but was 
itself of uncertain temperature. 
It was in July, 1895, that this experience vv^as obtained, and for a time the success 
of the research seemed doubtful. .During the vacation, however, an idea occurred to 
me which at once promised to do away with the wdrole difficulty. 
The Cooling and Luhricating of the Bushes. 
25. This idea consisted of what seemed to be a practicable plan of forcing a 
relatively small, but sufficient portion of the ice-cold water into the brake through 
each of the bearings, the quantities being strictly under control. 
That this plan should not have presented itself as soon as the addition of the 
stuffing-box and the cap were contemplated, becomes intelligible when it is remem¬ 
bered that the main object in the invention of this brake had been to secure a constant 
pressure in the air space within the vortices, so that by admitting the water through 
passa^ges in the vanes directly into this air space a constant resistance, whether that 
ot the atmosphere, or artificial atmosphere, on the entering water would be secured, 
and that the possibility of maintaining an even flow through the brake, so essential 
to any success in the research, depended entirely on the realization of this constant 
re-sistance. Except the inlet passage, the interior of the wheel, and the air space in 
tlie vortices, all the spaces in the brake and brake-case are under the full vortex 
pressure, excepting where, as in the bush on the closed side of the brake, and that 
between the solid disc faces on the inlet side, the pressure is relaxed by the 
escape of the water. This vmrtex pressure depends on the load on the brake, and 
may be anything up to 25 pounds on the scjuare inch greater than that in the air- 
cores. It thus seemed like starting de novo to interfere with this arrangement ; and 
it was only when one came to realize that the possibility of preventing all leakage b}’ 
the introduction of the stuffing-box and the cap had rendered it possible, by controlled 
subsidiary supplies under pressure, to reverse the flow of the lubricating water, and so 
to do away with leakage, and not only to secure lubrication, but also lo cool the 
bushes, and then only after considering the amounts of wmter required, and tlie pro¬ 
vision in the way of pumping appliances, separate supplies of water and thermometers, 
&c., that the altered facilities afforded by the circulating pump came to be recognized. 
