Chicago, March 6, 1905
I am truly sorry to learn that all the various members of your family have had the grippe, even if the attacks were mild.
I note that the measurements of the crow which you have secured agree closely with those of the Egyptian rook, as given by Mouillard. What do you figure to be the power which he expends at the speed you give of 24 miles per hour? I figured, as you know, that the buzzard, at 16 miles an hour, expended 140.8 ft. lbs. per minute for each pound of his weight, while you say that a flying machine will have a limit of 75 pounds supported per horsepower at 35 miles an hour, which amounts to an expenditure of 440 ft. pounds per pound of weight.
I am surprised that the speed should make so great a difference, in view of "Langley's law" (?), that the greater the speed the less the power in proportion.
I should be glad to have your figures whenever you have leisure and energy.
Wilbur Wright to Octave Chanute, March 11, 1905