3r0 MARITIME OBSERVATIONS. 
the refiftance occafioned by that friGtion, might be dimi— 
nifhed by putting greafe between them, yet that.a body 
fliding on a fluid, fuch as water, fhould have no need of | 
nor receive any: advantage from fuch greafing.. But the: 
fact is not difputed.. And the reafon perhaps may be this.. 
The particles of water have a mutual attraction, called the- 
attraction of adhefion. Water alfo adheres to wood, and 
- to many other fubftances, but not to greafe: On the 
contrary they have a mutual repulfion, fo that it is.a» 
queftion whether when oil is. poured on water, they ever. 
actually touch each other; for a drop of oil upon water, 
inftead of fticking to.the {pot where it falls, as it would if 
it fell on a looking-glafs, {preads.inftantly to an immenfe 
diftance in a film. extremely thin, which it could not eafily 
do if it touched and rubbed or adhered even ina {mall de- 
gree to the furface of the water. Now the adhefive force of 
water to itfelf, and to other fubftances, may be eftimated. 
from the weight of it neceflary to feparate a drop, which 
adheres, while growing, till it has weight enough to force: 
the feparation and break the drop off. Let us fuppofe the 
drop tobe the fize of a pea, then there will be as many 
of thefe adhefions as there are drops of that fize touching. 
the bottom of a veflel, and thefe muft be broken by the: 
moving power, every ftep of her motion that amounts to 
a drop’s breadth: And there being no fuch adhefions to: 
break between the water and a greafed bottom, may oc-- 
cafion the difference. 
So much refpecting the motion of veffels.. But we have 
fometimes occafion to ftop their motion ;. and if a bottom 
is near enough we can caft anchor : Where there are no 
foundings, we have as yet no means to prevent driving in 
a ftorm, but by lying-to, which ftill permits driving at’ 
the rate of about two miles an-hour; fo that in a. ftorm 
continuing fifty hours, which is not an uncommon cafe, 
the. fhip may drive one hundred miles out of her courfe; 
and fhould fhe in that diftance meet with a lee fhore, fhe 
may be loft. To 
