*Dayton, February 4, 1903*

Since I wrote you last Orville and I have done a little experimenting to determine
what shapes should be given to uprights, &c., to secure the minimum resistance.
The results are not altogether what we expected. The basis of our experiments
was a stick 2 ft. long, 7/8 in. wide and 1 1/2 in. deep. We found that rounding
off the rear corners *increased* the resistance nearly 5 percent; while
rounding the front corners reduced it to less than one half. Rounding both front
and rear brought it down to about one third. A surface like this

rounded in front and tapering toward the rear gave a resistance of nearly
one half. The same surface reversed gave a still greater resistance; and with
both front and rear sharpened it was greater still. That rounded front edges
were superior to sharpened did not surprise me as our experiments on the tangentials
of surfaces gave similar results in our last year's experiments. But the effects
of rounding and tapering the rear edge gave several surprises and some apparent
contradictions. Thus rounding the rear edges of a stick which is left square
in front will *increase* the resistance, while similarly rounding the rear
edges of a stick which is already rounded in front will still further reduce
the resistance. Why this rounding at the rear should cause an increase in one
case and a decrease in the other is the puzzle. I have confirmed the fact by
repeated experiments. The result is always the same.

A piece of strap iron 2 ft. by 1 inch gave a resistance of .21 lbs. in a wind blast moving 31 ft. per second. This would give a coefficient of a little less than .003, but if a deduction of 10 percent be made in the anemometer reading as per Prof. Marvin's report, then the coefficient would be about .0035. The coefficient of the stickrounded at front and rear

figures almost exactly .001.

I have not yet written up an account of our last year's gliding experiments,
but have promised Mr. Warder that I will have a paper for the Western Society
some time in June.

We are just now in the midst of the worst blizzard of recent years. Chicago is cut off from telegraph communication with the rest of the world and wires are down in many parts of the country. We envy you the sunny skies of Italy.

With kind regards to yourself and to the Misses Chanute, I am [&c.]