226 Improved Capstan and Windlass „ 
may have equal tension at the top and at the bottom of 
the barrels, and that the defect which conical barrels 
cause in this respect may be avoided. 
The small barrel should be furnished with falling palls 
as well as the large one ; a fixed iron spindle ascending 
from the deck will be the best for it, as it will take up 
less room. The spindle may be secured below the deck, 
so as to bear any strain, as the small barrel need not be 
much above half the height of the large barrel ; the cap- 
stan bars can easily pass over it in heaving round, when 
It is thought fit to use capstan bars on the same deck 
with the small barrel. As two turns of the messenger 
round both barrels will be at least equivalent to three 
turns round the common capstan, it will hardly ever be 
necessary to use more than four turns round the two 
barrels. 
The circumstance which prevents the lateral friction 
of the messenger in my double capstan is, that in it each 
coil is kept distinct from the rest, and must pass on to the 
second barrel, before it can gain the next elevation on the 
first, by which no one coil can have any influence in rais-, 
ing or depressing another ; and what each separate coil 
descends in a single revolution, it regains as much as is 
necessary in its passage between the barrels, where in the 
air, and free from all contact with any part of the appa 
ratus, it attains higher elevation without a possibility of 
friction or wear. 
I have described my double capstan, as it is to be 
used in large vessels, where messengers are necessary, 
from the great size of the cables ; but it is obvious that it 
is equally applicable in smaller vessels, as their cables 
can be managed with if in the same manner as is direct- 
ed for the messenger. The same principle may also he 
easily applied to w indlasses, by having a small horizon- 
tal barrel placed parallel to the body of the w indlass, and 
