TREAD-WHEEL

was practically invented by Sir W. Cubitt in 1818, and every male adult prisoner who has been sentenced to * hard labour ’ lias to be employed on the T.W. or other similar bodily labour for at least one month of his imprisonment. The steps are about 7^ inches apart, and 32 are taken a minute for 15 minutes, and the power is now utilized for Trevithick, grin fing com, pumping water, etc. The total time of t le labour is six hours a day, in two periods of three hours each, and five minutes’ rest is allowed at the end of every fifteen minutes.