274 Frictionless Plunger Pump. [Book III.

the estimation of engineers appears from the increasing employmentof it. It is, moreover, for äught that is known to the contrary, the parentof the common lifting pump; and to its inventor the double acting steam-engine of Watt is in some measure due, the efficiency of that noble ma-chine depending entirely upon closing the top of the cylinder and passingthe piston rod through a stuffing box—both of which had already beendone in this pump. Steam-engines have also been constructed on thesame plan as these pumps ; one long piston playing in two horizontal cy-linders, and the power transmitted from it by means of a cross-head at-tached to the middle of its length, and on that part which moves betweenthe stuffing boxes. Another celebrated machine is also copied from them—Bramah ’s hydrostatic press is one of Moreland’s pumps.

There is another species of plunger pumps in which the stuffing box isdispensed with, and consequently the piston works without friction. Asquare wooden tube, or a common pump log ofsufficient length, and with a valve at its lowerend is fixed in the well as shown in the figure.The depth of the water must be equal to thedistance from its surface to the place of delive-ry; and a discharging pipe baving a valveopening upwards is united to the pump tree atthe surface of the water in the well. The pis-ton (a solid piece of wood) is suspended by achain from a working beam, and loaded suffi-ciently with weights to make it sink. As theliquid enters the pump through the lower valve,and Stands at the same level within as without,whenever the piston descends, it necessarily dis-places the water, which has no other passageto escape but through the discharging pipe, inconsequence of the lower valve closing. Andwhen the piston is again raised as in the figure,a fresh portion of water enters the pump and isdriven up in like manner.

Dr. Robison observes that he has seen a ma-chine consisting of two of these pumps, madeby an untaught laboring man. The plung-ers were suspended from the ends of a longbeam, on the upper surface of which the manwalked, as on the picotah of India . He stoodon one end tili one plunger descended to thebottom of its tube, and he then walked to theother end, the declivity at first being about 25°, but gradually growing lessas he advanced. In this way he caused the other plunger to descend,and so on alternately.

By this machine a feeble old man whose weight was llOlbs. raised 7cubic feet of water 11-J feet high in a minute, and wrought eight or tenhours every day. A stout young man weighing 1341bs. raised 8J cubicfeet to the same height in the same time. The application of this pumpis extremely limited, and there is a waste of power in the water that isuselessly raised around the piston at every stroke.

The pistons of preeeding machines are made of solid materials; butthe pump now to be described has a liquid one. It was invented aboutthe year 1720, by Mr. Joshua Haskins, who made the first experiment withit in the house and presence of the celebrated Desaguliers . His design

No. 124. Frictionless Plunger

Pump.