74 DESCRIPTION AND TRIAL OF THE WINCHESTER. 
the theory will have to be adapted in some way to make allowance for the elevation of the 
surface which would take place in accordance with item 5 of the theory. 
“Curves prepared according to the theory indicate that the resistance is continually de- 
creasing as the length increases, and at a fairly rapid rate, although not nearly so rapidly 
as at the start. Using slightly different coefficients from those given in the paper, it is found 
that the horse-power absorbed in the friction of a 600-foot plane at 12 knots would amount 
to the product of the wetted surface by .0176, whereas Tideman’s coefficient is about 
.0312, or nearly double. I think the smaller coefficient cannot be true. 
