«60 
On Water Supplies suited to 
One source of power wliicli has unjustly fallen .into disfavour 
is wind. For such purposes as pumping, where, by means of 
moderate-sized storage tanks, provision can easily be made for 
■calms, and where irregularity of motion is of no consequence, 
windmills are of the greatest value, especially if they be so con- 
:^structed as to be automatic in the adjustment of their sails, both 
with regard to the direction of the wind and its force. 
It has been found that windmills, in this country, can be 
worked for about one-third of their time, hence their power and 
the capacity of the pumps should be three times greater than 
that which would be required to furnish the mean supply. 
A farmstead such as that of the Aylesbury Dairy Company, 
for example, requiring 2430 gallons per day, should have a pump 
capable of raising three times the amount, or 2430 x 3 = 7290 
.gallons per day, or 5 gallons per minute ; and the storage tank 
should hold at least a fortnight's supply, or 34,000 gallons. 
The practical difficulty in making use of wind-power for 
•domestic purposes lies in the automatic adjustment, which is 
essential where the apparatus is to work without supervision, 
and at small cost for repairs. Many varieties of windmills 
'have, from time to time, been introduced with this object, but 
few of them appear to answer this purpose satisfactorily, mainly 
•on account of the large number of joints and moving parts 
which the several systems have rendered necessary. Wind- 
mills on Halladay's system, however, which are largely used in 
North America, and specimens of which were exhibited by the 
'Ontario Pump Company at the Indian and Colonial Exhibition 
last year, seem to present advantages of design and construction 
which must recommend them strongly. 
The sails are of the disc kind (Figs. 8 and 9) ; but instead of 
being composed of a large number of individually moveable 
radiating sail-boards, they are arranged in six or eight groups, 
each group turning on pivots in the plane of the disc, and at 
right angles to the mean radius, so that when it is desired to 
reduce sail, the ends of the boards are presented to the wind, and 
not the edges, as in the common arrangement ; the effect being 
that less surface is presented to the wind, and the number of 
joints and sets of mechanism actuating them is reduced to six 
or eight. In addition, the sections are so hinged, that the 
centrifugal force due to increased speed of rotation helps to 
turn the sail-boards out of the wind, and so reduces the effective 
sail-area, thus giving the windmill considerable uniformity of 
speed in varying winds, and minimising the possibility of injury 
from heavy gales. 
The pivot of each section is connected by rods and bell- 
•cranks in a simple and substantial manner to a disc, sliding on 
