Chicago, July 4, 1901
I found the clinometer I was looking for, which is most applicable to the lengths of flight I hope you will make, and sent it.
The maker calls it an altimeter, and it is used as follows:
It is held in the right hand, and the sight directed through the tube to the point to be observed. The vertical limb being first unclamped it is moved until the bubble shows that its center coincides with the cross hair. The limb is then level, and is clamped with the left hand, when the angle can then be read off. I have found this instrument to give quite accurate results when carefully used.
Wilbur's response, July 6, 1901