788 The American Naturalist (September, 

I presented in this magazine certain papers of a suggestive 
character, the results of much observation and experiment, in the 5 
hope of directing attention to curious facts, not recognized, bear- 
ing upon this subject. Three years ago I moved to my present 
location, Egeria, Colorado, where, during the past eighteen 
months, I have done the principal work necessary for this under- 
taking. 
I consider myself successful in obtaining important results. 
In this paper I propose dealing with an experiment so obviously i 
simple, as it now stands, that I am dazed to think of the labor 
that has been expended upon it. This device, in wind, really 
exhibits the entire soaring case in a very concise way, so far as its 
fundamental principles are concerned; but I give briefly the same 
experiment in calm air, as supplementary. The first form of the 
experiment can be tried by any one with a fair amount of con- 
structive ability, and it cuts an awful chasm through the teachings 
of the mechanical schools on atmospheric resistance, and unerr- 
ingly pointg, to practical air navigation. 
A rough-board platform, about twelve feet square, with a post 
and cross-beam fixed upon it, the whole being capable of hori- 
zontal rotation to present the plane to the wind from whatever 
direction it might blow, is the framework. 
The plane should bė a flat pyramid,—5x5 feet square is a good 
size on the base, and two inches high. The edges of such 
shape, being sharp, give the effect of a true plane without thickness. 
The whole should be finished smooth, similar to the top of an 
ordinary piano. Perfectly seasoned white pine or red cedar is an 
excellent material to use, glueing thin strips together in the rough, 
and dressing to shape. 
To one edge of the plane two fine steel wires are fastened, 
which are suspended from two ordinary spring balances, fixed by 
their rings to the cross-beam of the platform. When thus sus- 
pended the plane will sway freely too and fro, like a child’s swing, 
the flat side being in a vertical position when at rest. 
To the apex at the back of the plane is fixed another wire pro- 
vided with another spring balance, the ring of which is fastened 
è to the rear part of the cross-beam, when the plane is drawn back- 



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