The world as seen through the clarifying lens of the 9th Edition of the Encyclopaedia Britannica (1875-1889).

Sunday, 20 July 2008

23 (iii) Modesty, thy name is Professor J. B. Pettigrew

"To Professor J. Bell Pettigrew is due the merit of having first satisfactorily analysed [wing] movements, and of having reproduced them by the aid of artificial wings. This physiologist in 1867 showed that all natural wings, whether of the insect, bat, or bird, are screws structurally, and that they act as screws when they are made to vibrate, from the fact that they twist in opposite directions during the down and up strokes. He also explained that all wings act upon a common principle, and that they present oblique, kite-like surfaces to the air, through which they pass much in the same way that an oar passes through water in sculling. He further pointed out that the wings of flying creatures (contrary to received opinions, and as has been already indicated) strike downwards and forwards during the down strokes, and upwards and forwards during the up strokes. Lastly, and most important of all, he demonstrated that the wings of flying creatures, when the bodies of said creatures are fixed, describe figure-of-8 tracks in space, - the figure-of-8 tracks, when the bodies are released and advancing as in rapid flight, being opened out and converted into waved tracks.

Professor Pettigrew's discovery of the figure-of-8 and waved movements, concerning which so much has been said and written, was confirmed some two years after it was made by Professor E. J. Marey by the aid of the "sphygmograph."

from FLIGHT, FLYING MACHINES in volume 9 of the Ninth Edition of Encyclopaedia Britannica. Author : Professor J. B. Pettigrew. Including credits to illustrations and tables, I count no fewer than 45 named citations of the illustrious academic, which must surely be some kind of record.

It is a great shame that for all the time and energy the professor invested in the study of flapping, not a single flying machine following that model has ever sustained flight. Perhaps surprisingly, J. B. P. was not entirely blinkered in his view of the problem of flight, and although containing a great deal on the subject of flapping, his article does eventually move into other areas.

"In flight, one of two things is necessary. Either the wings must attack the air with great violence, or the air in rapid motion must attack the wings : either suffices. [...] The flight of the albatross supplies the necessary illustration. If by chance this magnificent bird alights upon the sea he must flap and beat the water and air with his wings with tremendous energy until he gets fairly launched. This done he extends his enormous pinions and sails majestically along, seldom deigning to flap his wings, the breeze works for him."

The article continues at length, describing with enthusiasm projected and attempted models, in many (but not all) of which some kind of flapping motion is a key feature. It would be far fairer to Professor Pettigrew to reproduce his text in full : however fairness is not my object at this time, so we will finish with the professor's final, patriotic words, and do our best to forget two bicycle-salesmen brothers from Ohio.

"The unremitting efforts of Mr Moy and other British engineers to construct flying machines deserve well of science. They are significant as showing that the great subject of aerial navigation is at length receiving a fair share of the thought and energy of a country which has already produced the locomotive engine, and which, there is good reason to believe, is destined also to produce the flying machine."

[You can now enjoy the article FLIGHT, FLYING MACHINES in full at the 1902 Encyclopedia, complete with all illustrations.]

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