Mr Witty's Improvement lyn Pumps. 22S 
barrel. Mr Witty avails himself of this power in a very ingenious 
manner, Instead of letting the water or liquid escape from a 
common pump at the usual place of delivery, I caused it to de- 
scend again in a syphon-pipe to the lowest level at which it can 
conveniently be delivered ; and as this descent is considerable in 
ships, brew-houses, &c. a considerable saving of labour :is effect- 
ed in working pumps by a descending column of. water or li- 
quor, counter-baiaricing as much in length of the rising column 
in the pump, as the height which it descends in the syphon- 
pipe, to the place where it can be delivered." We have no 
doubt that this invention will be found to be of great practical 
value, as it relieves the men at the pump of a very great part of 
their labour. In cases of danger at sea, it may prove the means 
of saving both the ship and the crew. 
If we consider the water which in ordinary pumps falls from 
the top. of the barrel to the place of its reception, as a mechani- 
cal force which is lost, we may avail ourselves of it, by, various 
contrivances, for assisting in the work to be performedi In Mr 
Witty's contrivance, the men at the pump raise thewater to the 
bottom of the short leg of the syphon, and it is then drawn 
through the syphon by the action of the longer branch. There 
are many cases, however, when we may allow the' men to raise 
the water to the top of the barrel, and employ the direct force 
of the descending fluid to work another pump, or perform any 
other piece of work that may be required, 
7. Account qf Mr Gladstone's New AietJiod of . Propelling 
Steam-Boats. , ■ - 
Several years ago, Mr Gladstone, an ingenious mill-wriglit of 
Castle-Douglas, contrived a kind of bucket-wheel for giving 
motion to thrashing-mills, and other kinds of machinery % with- 
out knowing that he had been anticipated long ago by Mr Costar, 
This contrivance he has since modified, so as. to enable it to 
be applied to propel steam-boats, as shewn in Plate X. Pig. 4., 
where A is a shaft or axle of iron, passing in the usual manner 
through the sides of the ve.ssel. On each end of this shaft, on 
the outside of the said vessel, are firmly fixed two wheels of cast- 
* See the New Edition of Ferguson’s I,.ecture.s, voL ii. p. 57. 
