, 
MURPHY: POWER OF A TWELVE FOOT ‘CPOWER” WINDMILL. 1Q7 
ay 
ad a Cc my | 
en Qs 4 
ccurmmunicamemancemmens tas cesar Uh serena Musecnat Sa 
Le | 
ae Re Ly { 
Ry » Reif fi 
XQ “Rane 
Big, 3. 
In Fig. 4, AB represents the position of the strip at the begin 
ning of a second and A,B, that at the énd of the second. The 
wind at the beginning of second meets strip at A at the end of sec 
ond it meets it at D, that is, while the strip has moved a distance 
Ne 
lal 
eromeneies nee UD 
: 
iN Ob 
Ss ¢ 
> 
ON, 
Sy 
Se 
N 
4 
i 
4 
Fig. 4, 
vy it has moved in the direction of c a distance AD=vcotB. While 
it has moved this distance in direction c it has moved AE in the 
direction of v,==vcotBcosa. Hence the velocity producing pres- 
Surevis V==V,- vcotBcosa V c?--v? vcotBcosa (20) 
: 
