f 153 3 
II. Concerning the ratio between the velotity of 
windmill fails unloaded, and their velocity when 
loaded to a maximum . 
Thofe ratio’s, as they turned out in experiments 
upon different kinds of fails, and with different in- 
clinations (the velocity of the wind being the fame) 
are contained in column io of tab. III. where the 
extremes differ from the ratio of io : 7,7 to that of 
10 : 5,8 j but the mofl general ratio of the whole will 
be nearly as 3 : 2. This ratio alfo agrees fufficiently 
near with experiments where the velocity of the wind 
was different, as in thofe contained in tab. IV. col. 13. 
in which the ratio’s differ from 10 : 6,9 to that of 
10 : f,p. However, it appears in general, that where 
the power is greater, whether by an enlargement of 
furface, or a greater velocity of the wind, that the 
fecond term of the ratio is lefs. 
III. Concerning the ratio between the greateft load 
that the fails will bear without flopping , or what 
is nearly the fame things between the leaf load 
that will flop the fails , and the load at the maxi- 
mum . 
Thofe ratio’s for different kinds of fails and in- 
clinations, are collected in col. 1 1. tab. III. where the 
extremes differ from the ratio of 10:6 to that of 
10 : 9,2; but taking in thofe fetts of experiments 
only., where the fails refpedtively anfwered beff, the 
ratios will be confined between that of 10 :8 and of 
10:9; and at a medium about 10 : 8,3 or of 6 : f . 
This ratio alfo agrees nearly with thofe in col. 1 4 of 
tab. IV. However it appears, upon the whole, that 
in thofe inftances, where the angle of the fails or 
Vol. LI. X quan* 
