546
MOLESWOBTIl’ö l’OCKBT’BOOK
Windmills.
RULE FOR THE ANGLES OF THE SAILS.
A = Angle of the sail*with the plane of motion
at any part of the sail.
R = Total radius of sail in feet.
D = Distance of any part of the sail from the
axis.
A = 23"-^.
If the radius of the windmill sails be divided
into six equal parts, the angles at tach of those
parts will be as follows, reckoning from the axis:
Distances from axis .. .. | J- 3 | } I I tip-
Angle of sail with axis .. ,67|° 69° Jl|° T5° 79>° X5°
Angle of sail with plane of) 21 | 5
molion ........ 5 3 I | 2
Axis of shaft of windmill with horizon
= 8° on level ground.
= 15° on high exposed positions.
Breadth of whip at axis = -^th length of whip.
Depth „ „ - J^th • „
Breadth of whip at tip = ^Lth ,,
Depth „ „ = -Jr,th „
Width of sail „ = |rd ,,
divided by the whip in the proportion of
5 to 3, the narrow portion being nearest to
the wind.
Width of sail at axis .. = |tli length, of whip.
Distance of sail from axis = I th „
Cross-bars from 16 to 18 inches apart.