A Proposed Competition for Inventors of Flying Machines. To the Editor of the SCIENTIFIC AMEEICAN: After carefully studying the problems of mechanical flight for fifteen years, and noting the reports of experiments as they have appeared in your columns during that time, I venture the following suggestion in the hope that it might accelerate our progress. It must be assumed that the large prizes offered to the first successful aviator are offered in good faith; yet many of them have been offered for some years without being claimed or even competed for. If the amount of one or more of these prizes could be made available to conduct proper experiments, I believe the problems would be speedily solved. Designers of airships, even more than other classes of inventors, are without funds to reduce their ideas to practical forms. To meet this difficulty, I would invite the inventors to submit their designs in a competition in which competent mechanical engineers should be judges. The contest should call for good drawings and complete specifications clearly setting forth the invention or plan. Contestants should be permitted to summarize the objections likely to be offered, and to point out how they have met them in their inventions. By way of prize, financial aid should be extended to the inventor whose design seemed to the judges most practical and most likely to succeed if actually constructed. The right could be reserved to reject all plans submitted, which could be returned to the inventors without being made public unless with the inventor's consent. The donor of the prize could also reserve the right to participate in the patent fights and other profits of the successful competitor. This plan is respectfully called to the attention of those newspapers which have offered rewards for successful flight. It is worthy the attention also of any person of means, who might desire to promote the science of aerial navigation, and to share in the profits which may be made by the persons lucky enough to secure valid patents on the successful invention. Denver, Col., October 29, 1907. J. F. LAWSON. Flying Machine Economics. To the Editor of the SCIENTIFIC AMERICAN: I read with much interest the articles pertaining to flying machines, which appear so frequently in the SCIENTIFIC AMERICAN. There seems to be a great difference in the estimate of the power required to propel the machines of different inventors in proportion to their weight. There is also a great diversity in the estimated velocity at which the different machines will fly, and this difference in velocity is not accompanied by a corresponding difference in power developed. To illustrate: In the last number of the SCIENTIFIC AMEKICAN appears an article by the Paris correspondent, descriptive of the machine designed by Henri Farman. The weight of the machine, including the pilot, is 1,100 pounds; the speed, 3f miles an hour; power of the motor, 50 horse-power; area of aeroplane, 561 square feet. In the same article we have a description of the machine designed by A. V. Rowe, giving data and estimates as follows: Weight, 450 pounds; speed, 40 miles per hour; motor, 6 horse-power; area of aeroplane, 480 square feet. In reading such descriptions, the thoughful seeker after facts can draw either of the following conclusions: that the data pertaining to flying machines have not yet reached a scientific basis and that we have no trustworthy "flying machine economics," or if there is such a science, the inventors of flying machines seem to be entirely ignorant of its principles. In the two cases cited, one machine weighs 22 pounds to the horse-power and the other 75. The first has approximately 2 pounds to the square foot of aeroplane, while the latter has leas than 1 pound to the square foot, and the machine with ihe relatively large area of aeroplane and small motor has one-third more speed than the one with the relatively small aeroplane and higher powered motor. Is it true that there are no data obtainable that can furnish a fairly accurate theoretical basis for the experimenter to work upon? Can we rely upon the statement on the authority of Langley, that "a 1-horse-power engine can carry 208 pounds through the air at 40 miles per hour"? Let us analyze that statement. At 40 miles an hour, the velocity is 3,520 feet per minute. 1 horsepower, or 33,000 foot-pounds, would exert a thrust 33,000 through 3,520 feet of __, or 9.375 pounds, or less than 10 pounds. Now, to use a hypothetical illustration, is it true that a kite weighing 208 pounds can be made to fly in a 40-mlle breeze, with a pull on a horizontal kite-string of less than 10 pounds? That is what the statement amounts to, and there are a great many that are somewhat skeptical as to its truth. Now, it seems to some of the readers of flying machine literature that there has been enough experimental work done to establish what might be regarded as the fundamental principle of aeronautics with quite a degree of certainty. The principles of greatest importance, and seemingly the easiest to discover, would be the following: First. What form of air propeller is most efficient, and what is its efficiency? Second. What form of aeroplane has greatest lifting power, and what is its lifting power at different velocities for each horse-power expended in propelling it through the air? Third. What is the air resistance per square foot of surface exposed at a given velocity, and what the ratio of variation at different speeds? With most inventors of airships the conception of air resistance seems to be very peculiar. They assume great efficiency for their propellers and great lifting power for their aeroplanes, which means, of course, great air resistance, but at the same time, they expect the machine to move through the air at tremendous speed, with relatively little power expended, which means small air resistance. The most striking example of the latter anomaly is furnished by the designer of an airship a picture and description of which you will find inclosed. The weight is given as 100 tons; speed, 300 miles an hour approximately; and carrying capacity, 100 passengers; fare from Chicago to New York, or say 900 miles when the trip is made in three hours, $10 per passenger. In this example we can deduce the cost of fuel, and hence the size of the motor, from the data given; that is, the gross receipts for the trip. Now, we know it would require a constant lifting power of 100 tons to keep such a machine floating in the air, and whatever may be the method of suspension, the apparatus would necessarily present a very large area of cross-section frontage to offer resistance to rapid horizontal motion through the air. Therefore, to force such a structure through the air at a velocity of 300 miles per hour would require an expense for fuel out of proportion to the small carrying capacity and consequent income of the machine. While there is a great deal that we do not know about flying machines, in contemplating the future there are at least two predictions that can be made with a high degree of certainty; first, a flying machine will never be able to carry a given weight of paying load a given distance as cheaply as it can be carried on wheels; second, the speed of a flying machine equipped with the same power will never be equal to that of a vehicle on wheels, either rolling over steel rails or a smooth hard road surface. The chief obstacle to high speed is the air resistance. By high speed we mean a velocity exceeding 60 miles an hour. This is true no matter whether it is a locomotive on steel rails, or an automobile on the wave-swept course on the Florida beach. Since the weight of the flying machine must be supported by an aeroplane or other device, the area of frontage presented to the air must necessarily be much greater than that of a machine on wheels designed so as to offer the minimum air resistance. Again, the efficiency of an air propeller can never be made equal to that of the driving wheels of a locomotive or an automobile; hence the speed of the flying machine will be less on account of the greater resistance and less effective driving power. I am aware that these latter conclusions may be criticised by designers of flying machines, but I would like to know what explanation can be given to show that they are not correct F. E. STANLEY. ITosemlte Waters to be Conserved. A plan is on foot to conserve the waters that supply the Yosemite and Bridal Veil Falls so that each will flow three months more per year than at present. These falls usually go dry about August. By building reservoirs in the headwaters of Bridal Veil and Yosemite creeks, it is believed that sufficient water can be stored to maintain the flow over the falls until late in October. A preliminary survey indicates that the project is an entirely feasible one. Ordinary white phosphorus being very poisonous and injurious to handle, other forms of the element have been sought. Red amorphous phosphorus, which is not poisonous, is readily prepared by heating the ordinary variety to 250 deg. C. in a closed vessel under pressur, or excluded from air and water. It has not the same qualities, however, as the white crystalline variety. A red crystalline form, recently discovered in Germany, is made by heating to boiling a ten per cent solution of white phosphorus in phosphorus tribromide. This is not poisonous and is an efficient substitute for white phosphorus in making matches. As certain Eu-I'opean countries have forbidden the manufacture and sale of the white Variety, amorphous phosphorus and safety matches are coming into general use. The Current Supplement. Of the minerals composing the group called mica, practically only two are commercially valuable for their physical properties. Of these two varieties only one is found in deposits of commercial value in the United States. In the current SUPPLEMENT, NO. 1665. Douglas B. Sterrett discusses these deposits in a thorough article. Dr. Alfred Gradenwitz tells how sensitiveness of photographic plates may be ' determined mechanically. Gas-engine valves is a subject upon which E. F. Blair writes instructively. Much interest is manifested among English tin miners in a new process of concentrating ores by oil. The English correspondent of the SCIENTIFIC AMERICAN describes this process at length. The last installment of Mr. Morrison's treatise on the development of armored war vessels is presented, the subject being modern American armor. Building a transatlantic liner is the subject of an article by the Berlin correspondent of the SCIENTIFIC AMERICAN, the vessel selected being the "Kronprinzessin Cecilie." Various methods of recovering rubber from wastes are described. Another technological article of interest is one on verde antique finish, its rapid production, and the method of obtaining the various shades. Dr. Lee de Forest writes on the audion, his new receiver for wireless telegraphy. The eucalyptus trees of Australia are technically considered by Henry S. Smith. Dr. Charcot's Antarctic Expedition. About the end of next July, Dr. Charcot, the French explorer, Vho recently passed two years in the Antarctic exploring the great continent there, expects to again continue his work already begun. The French Acadmie des Sciences, and other learned bodies, are urging the French government to pay a part at least of the $160,000 that the expedition to explore this continent, which is as large as Europe and Australia combined, will cost. The remainder left unpaid by the French government will be raised by private subscription. The explorer will spend two years at the work. Although exploration is the main aim of Dr. Charcot, a great deal of time will be spent in carrying on investigations to substantiate the theories set forth by Prof. Gaudry, of the Acadmie, who holds that the discovery of fossils in Patagonia destroys a great many of the formerly-held ideas concerning the progress of evolution. He says that "this development does not appear to have had the same continuity in the two hemispheres, and it is to further discoveries in the Antarctic that we must look for a solution of that great problem, the origin of life." The discovery of Dr. Nordenskjold, who found fossil imprints of tropical plants in the Antarctic, proves that there was once in the neighborhood of the South Pole a rich and abundant vegetation. The ship that is to carry the expedition to their working ground was especially built for it at St. Malo. It will be a vessel of 800 tons burden, and have 500 horse-power engines capable of producing a speed of eight knots. A supply of 230 tons of coal and 120 tons of miscellaneous material will be taken for the voyage. Thirty men, nearly all of whom took part in the expedition two years ago, will comprise the crew. An Important Change In Editing the Official Gazette of tlie Patent Office. Owing to the constantly increasing number of patents issued each week in the United States, all the claims of a patent will appear in the Oiflclal Gazette only when they do not exceed five in number. Where patents have more than five claims, only five of the claims will be printed, and the number omitted will be indicated. Henceforth it will not always be possible to ascertain from the Oiflclal Gazette all of the features covered by a patent if the patent is issued with more than five claims. If a public library with the monthly volumes containing the complete copy is not accessible, it will be necessary to obtain a copy of the patent. As the number of copies of patents printed each week is limited, the supply is rapidly exhausted. Following the statement made by Sir William Ramsay that a solution of copper sulphate in distilled water shows in the spectroscope the characteristic red line of lithium when placed in contact with the emanation from radium, comes the report that the German chemist Dr. Theodore Grosse has succeeded in breaking up the element platinum. He for a number of hours subjected potassium carbonate, maintained at a high temperature in a platinum vessel, to the action of an alternating current between platinum electrodes. After some time, the electrodes became coated with a deposit of charcoal-colored crystals, and gave evidence of having been attacked, both the electrodes and the containing vessel losing weight. On extracting the melt, a brown powder free from carbon or potassium was obtained. Although both the crystals and the powder gave solutions from which they were precipitated by hydrogen sulphide, the presence of platinum could not be detected.
This article was originally published with the title "Correspondence"