experiments has already been given; in the main the work of previous investigators receives confirmation (Fig. 94, Chap. VI., § 148).
§ 237. Langley's Experiments. The “Rolling Carriage.”—This instrument is a highly specialised contrivance for investigating the law of pressure on the normal plane, and for determining with a greater degree of accuracy than previously the value of the constant relating to same.
The instrument consists of a frame beautifully mounted on friction rollers, and recording direct on a chronograph barrel. The wind plane is attached to the front end of a bar, carried forward from the frame and clamped thereto, the pressure on the wind plane being taken by a carefully calibrated spring and the deflection recorded on the chronograph drum.
The experiments made with this instrument proved disappointing, the results, owing to the open air conditions, being no more consistent than those previously obtained with the resultant pressure recorder. The value of cited in Chap. VI., is that given by Langley as determined by the rolling carriage; the value, however, is substantially the same as that previously ascertained with the earlier instrument.
§ 238. Langley's Experiments. Summary.—Prof. Langley concludes his account in the Memoir with a summary. Much of this deals with the question of the power required for flight, where naturally the same error is made as elsewhere m the work, the energy necessary to support in a frictionless fiuid alone being taken into account.
It is from no wish to belittle the work of the late Prof. Langley that attention has so frequently been drawn to the point at issue. Langley's name will always stand as one of the most distinguished pioneers of experimental aerodynamics. The whole of the mis-statements to which attention has been directed hinge upon the one fundamental error, that of the assumption of the
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