498 Dr. stedman on the Degrees and Quantities 
the heavier kinds, and of confiderable fridtion, may he 
fuppofed to he kept in motion; which, to the times 
wherein they cannot go, is as j o to 17. 
It may he obferved, that the refiftance to the machine, 
or its weight and fridtion, being diminifhed, though in a 
fmall degree, will add confiderably to the frequency and 
length of times in which it can go ; fince it often happens 
that there are winds immediately below the lowed: de- 
gree in the preceding eftimate, fufficient to keep the 
lighter machines in motion. Hence thofe who have 
machines which are not abfolutely of the heavieft kind,, 
will be apt to conclude this computation erroneous. Be- 
ll des, there are few who make allowance for, or attend 
to, the univerfal law which obtains in mechanics, that in 
larger machines, their power doth not increafe in a pro- 
portion fo high as their bulk and the refiftance ariling 
from their fridtion. 
Computations of this nature, if carried on for a fuffi- 
cient length of time, might be of Ibme ufe in regulating 
infurances, or in pointing out the rilks of nautical ad- 
venturers, when made in the fame climates with the 
calculation of winds. 
Here I fliould have concluded ; but having, after writing 
what is above, committed thefe tables and obfervations 
to the examination of a learned member of your So- 
7 ciety, 
