322 REPORT—1852. 
comitant also of the same principle, that the very simple and advantageous 
mode of regulating the power of the wheel by the moveable guide-blades 
already described can be introduced. This mode, it is to be observed, while 
giving great variation to the areas of the entrance orifices, retains at all times 
very suitable forms for the converging water channels. 
Another adaptation in the vortex is to be remarked as being highly bene- 
ficial, that namely according to which, by the balancing of the contrary fluid 
pressures due to half the head of water and to the centrifugal force of the 
water in the wheel, combined with the pressure due to the ejection of the 
water backwards from the inner ends of the vanes of the wheel when they 
are curved, only one-half of the work due to the fall is spent in commu- 
nicating vis viva to the water, to be afterwards taken from it during its 
passage through the wheel; the remainder of the work being communicated 
through the fluid pressure to the wheel, without any intermediate generation 
of vis viva. Thus the velocity of the water, where it moves fastest in the 
machine, is kept comparatively low; not exceeding that due to half the 
height of the fall, while in other turbines the water usually requires to act at 
much higher velocities. In many of them it attains at two successive times 
the velocity due to the whole fall. The much smaller amount of action, or 
agitation, with which the water in the vortex performs its work, causes a 
material saving of power by diminishing the loss necessarily occasioned by 
fluid friction. : 
In the Vortex, further, a very favourable influence on the regularity of the 
motion proceeds from the centrifugal force of the water, which, on any in- 
crease of the velocity of the wheel, increases, and so checks the water supply ; 
and on any diminution of the velocity of the wheel, diminishes, and so admits 
the water more freely ; thus counteracting, in a great degree, the irregularities 
of speed arising from variations in the work to be performed. When the 
work is subject to great variations, as for instance in saw-mills, in bleaching 
works, or in forges, great inconvenience often arises with the ordinary 
bucket water-wheels and with turbines which discharge at the circumference, 
from their running too quickly when any considerable diminution occurs in 
the resistance to their motion. 
The first vortex which was constructed on the large scale was made in Glas- 
gow, to drive a new beetling-mill of Messrs. C. Hunter and Co., of Dunadry, in 
County Antrim. It was the only one in action at the time of the Meeting 
of the British Association in Belfast ; but the two which have been particularly 
described in the present article, and one for an unusually high fall, 100 feet, 
have since been completed and brought into operation. There are also 
several others in progress ; of which it may be sufficient to particularize one 
of great dimensions and power, for a new flax-mill at Ballyshannon in the 
West of Ireland. It is calculated for working at 150 horse-power, on a fall 
of 14 feet, and it is to be impelled by the water of the River Erne. This 
great river has an ample reservoir in the Lough of the same name; so that 
the water of wet weather is long retained, and continues to supply the river 
abundantly even in the dryest weather. The lake has also the effect of 
causing the floods to be of long duration, and the vortex will consequently 
be, through a considerable part of the year, and for long periods at a time, 
' deeply submerged under back-water, The water of the tail race will fre- 
quently be 7 feet above its ordinary summer level; but as the water of the 
head race will also rise to such a height as to maintain a sufficient difference 
of levels, the action of the wheel will not be deranged or impeded by the 
floods. These circumstances have had a material influence in leading to the 
adoption in the present case of this new wheel in preference to the old breast 
or undershot wheels. 

a 
