Twin water gate opened together by falling counterweights
Cutting a cord at b releases weights a–c to open the mouths m–r simultaneously
The upper drawing shows an undulating conduit or gate-frame carried on supports, with valve mechanisms at each end lettered M, a, f, b, n, c, r. The note explains a device in which cutting a cord at the midpoint b releases equal counterweights at c, which fall and open the two mouths m–r at once; the weights and their instruments must be exactly equal so the two mouths open together and no water is lost. The lower sketch shows a further mechanism set on an incline, labelled with a force ratio (100 of force to 10000 of water) and the words 'for the log-floats'.
On this page
Synchronised valve gear (M a f b n c r)
Fill first at f n while m r is stopped. Then close f n well and cut the cord across its middle at b, and at once the counterweights at c fall and open the mouths m r. The instruments that open the two mouths must be in every respect of equal quality.
Equal weights for a simultaneous descent
The cord must be cut exactly in the middle so that, the weights at c being of equal gravity, one side is not heavier than the other; an unequal cord could delay the descent and open one mouth before the other, and the lost water could never be restored.
Force ratio for the log-floats
The lower mechanism on the incline is annotated 'water – 10000 – 100 of force – 10000', a ratio of applied force to water moved, with the note 'for the log-floats'.