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Open Sights vs. Peep Sights To the Editor of the SCIENTIFIC American : Articles on the above have appeared in your issues of Dec 11, 1915, January 22, 1916, and April 15, 1916. These articles are by Mr. Crossman and Mr. Winans. Mr. Crossman states that the peep is quicker than the open. He also states that the open sight is used when in a great hurry. These contentions appear to contradict. He states that the peep is ignored. He also states that the peep must be found, that the head must be placed in the right position so as to look through the peep, that the peep must be looked through at the outset. These contentions look very much like further contradictions. It certainly does not seem possible to ignore the peep, and at the same time search for it. Mr. Winans states that the peep is useless in poor light, which lasts about half the time. Mr. Crossman does not deny this statement, hence must be taken to have admitted it. The same thing applies to Mr. Wi- nans' statement that the peep is useless for moving targets. Neither Mr. Crossman nor Mr. Winans states how useless the peep would be in the mud and slush of France and Belgium. The reason why the open sight is used when in a hurry is that the target, the front sight, and the surroundings are never lost sight of, as Mr. Winans states. On the contrary, when the peep is used the front sight, the target, and the surroundings are lost to view from the time that the plate which contains the peep comes before the eye until the peep is found, the head got in the right position, and the peep is looked through. After these things have been accomplished, the front sight must be searched for and found, the surrounding country must be searched over and the target found. When all these tasks have been performed the gun must still be sighted. When in a hurry, when the light is poor, and when the object is moving the peep is manifestly unfitted for use. Unquestionably, the peep, when it can be used, is more accurate than the open sight. The telescope is more accurate than either, but that fact would not justify the general use of the telescope. The accuracy of the peep induced both Americans and Canadians who were after mere amusement at the target to adopt the peep. The hope of securing trophies by somewhat questionable methods, that is, by the use of sights unsuited for war purposes generally, induced both Americans and Canadians to adopt the peep in foreign competitions. Mr. Crossman speaks of accuracy. He also advocates the use of a battle sight, which does away absolutely with anything resembling accuracy. His two positions on accuracy seem at least queer. What would be thought of a man who started out to hunt game with only a battle sight on his gun? The man who would do it would certainly be considered a little peculiar. Precisely the same thing applies to hunting men. The meaningless term “ flat trajectory” appears to have led some men astray. There never was and never will be a flat trajectory. As to accuracy of guns, which is another meaningless term or phrase, no gun is accurate. No gun can 1.Je sighted. Sighting is mere approximation. I do not refer to battle sights, which are never intended to be sights at all. Curiously, neither those who make guns nor those who use them seem to desire that guns should be more nearly accurate than they now are, though they could very easily be made more nearly accurate. C. C. GRANT, M.D. Box 422, Red Deer, Alberta. Possibilities of the Transatlantic Flight To the Editor of the Scientific American : In your issue of May 6th is presented, in a letter in the Correspondence Column, by George Lanzius, an elementary proof that the “ average machine “ cannot fly across the Atlantic in a non-stop voyage. “ These figures,” it is stated, “ prove conclusively that the nonstop flight across the Atlantic is beyond the present possibilities." The writer concludes by censuring Mr. Curtiss for lending his name to such a project. “ It is inconceivable to me,” says he, “ that any persons having even a slight knowledge of aerodynamics would lend their names and endorse such an undertaking." Permit me, by use of the writer's method of argument and somewhat better data, to prove the possibility of a non-stop flight across the Atlantic. Mr. Curtiss says he can build a 3,600-pound flying boat of 600 horsepower, using .55 pounds of fuel per horse-power. The weight per horse-power is, therefore, as follows: Fuel for 30 hours 16.5 pounds per horse-power The machine 6.0 “ “ " Two pilots 0.5 “ “ Total 23.0 «" " This 23-pounds load requires 23/6 = 3.83 pounds thrust per horse-power, whereas a propeller of 100 per cent efficiency can exert a thrust of 5.36 pounds at 70 miles per hour, the assumed speed. The ratio, 3.83 5.36 = 71 per cent, is, therefore, the necessary propeller efficiency in Mr. Curtiss's proposed craft. But he can build propellers having greater efficiency than is here found necessary. Furthermore, it is not necessary to fly at 70 miles an hour for 30 hours, since the proposed route to Ireland is only 1,800 miles long. Having proved from the data supplied by Mr. Curtiss that the non-stop flight is possible, I may remark that he is not pledged to such a flight with the machine above referred to, but has made provision for stopping en route for supplies from a ship. It thus appears that Mr. Curtiss is not, for want of “ a slight knowledge of aerodynamics,” venturing upon an ill-considered or a preposterous enterprise. On the contrary, he has an aerodynamical laboratory of his own, a technical staff of trained and experienced aeronautical engineers, and has had himself the largest practical experience of any man in America in the construction of varied types of aircraft. A. F. Zahm. Buffalo, N. Y. The Giant Kew Pine To the Editor of the Scientific American : I was interested in reading Mr. John Beach's letter in your issue of January 15, 1916, identifying the Giant Kew pine with the variety known in Florida as the Smooth Cayenne. I doubt the latter could ever reach the proportions of a Giant Kew, given suitable climatic conditions, and although the two may be allied, they may not be synonyms of the same variety. Still, I may be wrong. The Giant Kew was first introduced from the Kew Gardens to Ceylon, where, I believe, it was grown at the Botanical Gardens, Peradeniya. The variety did not appeal to the people especially, as the plant required some amount of cultivation and attention, and, if grown at all, it was only in small patches. Later, when the plant was distributed farther East, the innate industry of the Chinese quickly brought it to the fore, and large quantities are annually grown (especially in Sarawak) both for local and outside consumption. The natives here call the variety “ Nanas Pound,” but otherwise the recognized name is “ Giant Kew,” and even the R. B. Gardens of Peradeniya, to which I had the pleasure of supplying a few thousand suckers while in Ceylon, knew it by that name, and it is the only name under which Messrs. William Bros., of Hen- eratgoda, Ceylon, trade in. If the variety is an exotic, it is more so out East than West, and as far as I am aware, this variety has no disease out here, but not a little damage is done to mature and ripe fruits by nocturnal rodents when grown in the vicinity of jungles and forests. It is quite possible that Giant fruits do not travel well, owing to the pericarp softer and the fruit itself more juicy and than any other variety, but for canning and dessert purposes there are few fruits that beat it. W. L. Vander Slott. Department of Public Works and|Surveys, Kuching, Sarawak. The War Game Series To the Editor of the SCIENTIFIC American : Permit me to thank you for your attention in the matter of the war game. This project, undertaken by a publication of the standing and circulation of the SCIENTIFIC American, while in a way a novel departure for any other than a service magazine, is worthy of great commendation as educating your readers in a matter of such great present importance. Any student of the war game will receive a very excellent idea of the methods and procedure of modern military practice, and he is bound to derive considerable instruction along the lines covered. The military students, for example, officers and men of 'the National Guard, or members of the Business Men's Training Regiment, who are pursuing military studies should find the course covered by your war games of very material assistance in their work. In my opinion, the Scientific American, in thus presenting such a game, performs a great public service. John F. O'Ryan, Major General. Headquarters Division, National Guard, New York, Municipal Building, New York.
