CORRESPONDENCE.
SCIENTIFIC KITE.FLYING.
[To THE EDITOR Or viii " SPECTATOR:1
SIR,—.As I may fairly claim to have been the first to rescue the kite from the playground, to which it had been relegated for some centuries, and to inaugurate what has been termed scientific kite-flying, I may perhaps be permitted to comment on your review of Mr. Woglom's " Parakites " in the Spectatct- of April 17th. A perusal of the article under the above beading makes me regret that so much powder and shot should have been wasted over such an imperfect exposition of the present state of kite aerostation. Mr. Woglom, either consciously or unconsciously, appears to have flown his kites and written his booL in almost complete ignorance of what has been done not only in Europe and Australia, but also in his own country. At all events, when some little time back my attention was drawn to his book, I found an almost total absence from it of any reference not merely to my own work in 1883, but to the numerous developments and experiments made by what is rapidly becoming an international legion of scientific kite-fliers.
It is of no great importance to dive into the past in order to discover whether the Japanese used kites for military pur- poses, but I think your reviewer need not "demur at accept- ing the author's statement as to its early use in warfare." In the Chinese encyclopmdia., " Khe-tchi-King-Youen," we are told that about B.C. 206 the Chinese General, Han Sin, invented the kite in order that the inhabitants of a besieged city might communicate with the outside world. This is a record of far greater antiquity than the one quoted by Mr. Woglom from Japanese history.
The development of scientific kite-flying within the last fifteen years has also been far more extensive than would be inferred from a perusal of " Parakites." My own experiments were undertaken in 1883 to 1885, after which date a pressure of other work prevented me from further extensions. In these experiments, kites were flown tandem, with cupcone tails, and attached by steel wire, recom- mended to me by Lord Kelvin. At intervals on the wire Biram anemometers were attached, and the wind velocity measured at different heights above the ground. Aerial photography was also first accomplished in 1886. Since this date M. Batnt, of Eulaure, Mr. Eddy, of New Jersey, and Captain Baden-Powell, of London, have developed kite photography a good deal beyond the point reached by Mr. Woglom. Your reviewer seems to be rather sceptical as to the practicability of flying kites at great altitudes for the purpose of making weather observations. Probably he was unaware of the great progress which has been recently effected in this line by Mr. Lawrence Rotch and his assistants at the Blue Hill Observatory near Boston. I myself assisted at a flight there last year, when a Richard meteorograph attached to a tandem of kites was floated up to 6,000 ft. above the spot where we stood, holding on to the reel of wire. Since that time a height of nearly two miles (actually 8,740 ft.) has been attained, and with new apparatus constructed by the aid of a grant from the Hodgkins Fund of the Smithsonian Institution, it is expected that records will be brought down from a height of three miles. That such observations will be of immense value not merely for temporary weather observations, but for permanent climatic purposes, is obvious. Man lifting has also passed the stage of speculation and entered that of solid accomplishment. Both Captain Powell and Mr. Hargrave, of Australia, have elevated themselves (the former to 100 ft.) above the ground by the aid of kites ; and Mr. Hargrave goes so far as to say that a man with five of his new portable kites, which can be folded under his arm, might contemplate an ascent from the top of an omnibus with comparative ease and safety. In such a case, however, I fancy it would be as well to anchor the omnibus ; otherwise the bold serostatist might find himself travelling aerially per omnibus towards the enemy.
The other uses of kites, such as carrying despatches between ships, raising aerial torpedoes, floating electric-light signals, are all receiving attention, and our own naval authorities are just now officially experimenting with a view to their possible adoption for intership communication in time of war. A really scientific treatise on kites, by Professor C. F. Marvin, of the American Weather Bureau, has just been published in the official monthly weather review. It is entitled "Kite Experiments at the Weather Bureau." In this the whole subject of kites is for the first time ex- haustively and mathematically treated. Their theory is thrashed outs even to the consideration of eddy effects ; their varieties, plane, cellular, &c., fully described ; the best materials of which to make them, the details of construction, the conditions for their maximum efficiency, and the results of experiments with thirty-six kites of all existing modern patterns, are all dealt with most completely. Even the theory of tandem flight is worked out with catenary equations. Nothing is left to vague supposition.
The appearance of such a work, published as an official supplement to the weather-report, may be taken as some indication of the position to which kites have now attained as Lids to scientific research. I commend the perusal of this excellent work to the attention of both Mr. Woglom and the writer of your article. Professor Marvin does not indulge his romantic fancy by calling his kites 'Libby' or Realie.' They are rather on the convict plan of No. 1, 2, Ste.; but his conclusions are more likely to receive the assent of the scientific world than the fantastic and partial work of Mr. Woglom.
It is something to be able to find, according to Professor Marvin, that a kite can be flown safely at an angle of 65° to the horizon, so that instead of the "six miles of twine" sug- gested by "the boyish recollections" of your reviewer, it would not require more than two miles of wire to reach a height of 6,700 ft. As a matter of fact, Professor Marvin has several times reached a similar elevation with only 9,000 ft. of wire. I fear "one's boyish recollections" are hardly a safe basis to rely upon in these fast-moving days.
The great interest which has been recently taken in kites is due not so much to the discovery of their suitability for aerostatic purposes as to the fact, now well assured, that the kite or static aeroplane is the basis of the flying machine,. or movable aeroplane. The most efficient kite, when supplied with motive apparatus, is the best flying machine.
Hargrave, the great Australian kite-builder, is experiment- ing with kites half his time, and building his engine and motor the other half. The eyes of Langley, Chanute, Maxim, and other flying machinists are all turned towards the kite- fliers to solve half their difficulties ; and it may be safely argued that in proportion as our knowledge of the practical conditions of kite-flying increases, our realisation of aerial flight will approach its fulfilment. Apart from the lessons they teach to aeronauts, kites have now fairly entered the arena of practical politics as serious rivals to captive balloons. Every- thing accomplished by the latter, except during an absolute calm, is performed better by kites since, as Mr. Lawrence Rotch remarks in his short paper read before the Meteorological Society on April 21st, "The Blue hill kites fly in all weathers whenever the wind blows between twelve and fifty miles an hour, whereas captive balloons are driven by strong winds along an arc whose radius is the lifted cable,. and thus transmit violent shocks to the suspended instra- ments." They are also vastly cheaper and more portable than captive balloons. Some two years ago I suggested the formation of a Kite Corps to the Indian military authorities, especially for the purpose of aerial reconnaissance. Captain Baden-Powell has advocated their use for similar purposes in this country. In a chapter entitled "Suspension and Flight, in the Atmosphere," in a little work, "The Story of the Atmosphere," which will be published by Newnea and Co. in a few days, I have put the leading points forward in regard to the scientific uses of kites both as aerostats and, as Pro- fessor Langley terms the flying machines, aerodromes.-1
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