ON THE MECHANICAL EQUIVALENT OF HEAT. 
421 
into the brake. On the top of the brake is seen the new air-passage, of flexible incliarubber, leading 
to the vessel in which is the artificial atmosphere, which is connected with the large mercury-gauge on 
the left, also with the syringe. The automatic outflow cock is clearly seen under the brake, also the 
curved flexible pipe, covered with cotton wool, which receives the water from the outflow cock, leading 
to the fixed pipe behind the regulator, also covered, in which is the bulb of the outflow thermometer, 
and immediately over this the glass thermometer chamber, with its indiarubber continuation leading 
back into the main outflow channel which rises up behind the inlet thermometer chamber, till it turns at 
right angles into the condenser. Behind and on the left of the brake are seen protruding the stems of 
the thermometers for measuring the difference of temperature in the stuffing-box and the near bearing. 
Of the two bottles standing on the floor, that on the left is collecting the leakage from the stuffing-box, 
and the other the leakage caught in the indiarubber bag enclosing the automatic outflow cock. 
PLATE 6. 
This is a back view. On the left, close in front of the tank on the weighing machine, over which is 
the condenser leading to the switch, is seen the l^-incli quintuple centrifugal pump, with its driving- 
gear and the pipe supplying it from the service tank. On the other side of the 3-inch pipe for 
condensing water for the engines, and partly behind it, is seen the pipe leading from the pump up and 
along behind the 3-inch pipe, then down again into the ice-tank (on the e.xtreme right of the plate) ; 
through this it passes in a coil, emerging from the cover again as the covered pipe rising obliquely- to 
the regulator and inlet thermometer chambers (not seen), w-ith the branch to the pressure-gauge. The 
small horizontal branch coming through from beneath the pressure-gauge, continued by the covered 
indiarubber pipe, passing behind the vortex vessel of the speed-gauge to the stuffing-box, is one of the 
by-paths taking ice-cold water to the bushes; that on the left is behind the brake. The outlet ther¬ 
mometer chamber, with its indiarubber continuation to the main outflow channel into the condenser, is 
also clear ; as are also the belt and pulley- driving the paddle in the ice-tank. 
PLATE 7. 
This is again a back view, but taken so as to show the appliances up to the end of the engine-room, 
not seen in the previous plates. In the middle front is seen the 6-inch quadi-uple centrifugal pump in 
circuit, with the rising 4-inch main from the lower tank to the tank in the toAver (§3), together with 
the belt from the line shaft by- which this pump is driven. Immediately on the left of this plate, 
standing on a bench, is the end of the 3-inch quadruple vortex turbine, didven by Avater from the 
tower, and driving by a cord the 14-inch quintuple centrifugal pump. The standard, the lever, and the 
large riding weight of the Aveighing-maehine, with the tank behind, are completely- in vieAv; and over 
these again appears the condenser for cooling the eflluent water, passing to the end of the room and 
returning underneath to the stand-pipe and thence to the switch. 
PLATE 8, 
This is from a photograph of the apparatus for correcting the high temperature thermometer. On 
the table is the barometer, and to the right is the vapour chamber, in Avhich the thermometer is immersed 
through the coi-k on the top as far as to leave the top of the mercury A’isible. The escape passage and 
regulator are seen on the right. The pipe leading from the top is the connection of the vapour chamber 
with the lower mercury chamber in the barometer. This, after passing through the flask, receives by 
the branch (seen) a slight current of air from the pressure reservoir, with the top of which it is connected 
by a restricted pipe, so that the current is so slow that the resistance is negligible, though sufficient to 
prevent the vapour passing to the bai’oraeter; the pressure of air in the reservoir is shown by the large 
