The third wheel went into operation on the 24th December, 1822, and is of the same size as the second, and works under the same head and fall, making thirteen revolutions in a minute with a five feet stroke of the pump, and raises one and a half million gallons of water in twenty-four hours. It is not doubted that the second wheel can be made to raise an equal quantity, thus making the whole supply upwards of four millions of gallons in twenty-four hours.

The wheels are formed of wood, and put together with great strength the shafts are ;

The great size and weight of the wheel give it a of iron, weighing about five tons each. momentum which adds greatly to the regularity of its motion, so necessary to preserve the pumps from injury under so heavy a head as they are required to work, which is a weight of 7,900 Ibs., the height ninety-two feet.

" The pumps are placed horizontally, according to a design of Mr. F. Graff, and are worked by a crank on the water wheel ; they are fed under a natural head of water, from the forebags of the water wheel, and are calculated for a six feet stroke but hitherto it ;

has been found more practicable to work with not more than five feet. They are double forcing pumps and are connected, each of them, to an iron main of sixteen inches diameter, which is carried along the bottom of the race to the rock at the foot of Fairmount, and thence up the bank into the new reservoir. At the end of the pipe there is a stop-cock, which is closed when needful for any purpose. The shortest of these mains is two hundred and eighty-four feet long the other two are somewhat longer.