282 



SCIENCE 



[N. S. Vol. XXX. No. 765 



SCIENTIFIC BOOKS 

 Artificial and Natural Flight. By Sir HmAM 



Maxim. New York, The Macmillan Co. 



$1.75 net. 



Sir Hiram Maxim, the celebrated inventor 

 and manufacturer of the machine gun which 

 bears his name, has published in a book of 

 165 pages an account of the experiments which 

 he made for and with a flying machine from 

 1889 to 1894, and he has supplemented this 

 with his own observations and reflections, so 

 as to form a valuable guide to others who may 

 contemplate like work. 



The preface and the introductory chapter 

 bestow some hard slaps upon mathematicians 

 who have written upon aviation; for Mr. 

 Maxim believes that practical experiment 

 alone is to be relied upon, and he states that 

 all the successful flying machines of to-day 

 are built upon the lines which he had thought 

 out and found to be the best. 



In the chapters upon Air Currents and 

 upon Kites he describes some very interesting 

 observations upon the rising trends of winds 

 with which soaring birds probably perform 

 their astonishing feats. He expresses the be- 

 lief, however, that "we shall never be able to 

 imitate the flight of the soaring birds. We 

 can not hope to make a sensitive apparatus 

 which will work quick enough to take advan- 

 tage of the rising currents of air." It is pos- 

 sible that Mr. Maxim is mistaken. 



Then he gives an account of his experiments 

 upon screws, on the coeificient of air resistance 

 of various forms, on the best shapes for aero- 

 planes and for condensers and then passes to 

 hints as to the building of flying machines, 

 which it is greatly to be hoped he will apply 

 himself, now that the success of others has 

 removed the odium which attached to such 

 experiments less than fifteen years ago. 



Mr. Maxim discusses briefly the Santos- 

 Dumont, the Farman, the De la Grange and 

 the Bleriot flying machines, while he expresses 

 doubts in the main body of the book as to the 

 truth of the " alleged flights " of the Wright 

 Brothers, which he takes back in the appendix. 

 His calculations of resistances and horse power 

 required are somewhat vague; he figures for 



the De la Grange machine that at an angle of 

 incidence of 1 in 10 the screw thrust would be 

 100 poimds, requiring 10.66 H.P. to overcome 

 the drift, and he allows another 10 H.P. for 

 the atmospheric resistance due to the motor, 

 the man and the framework of the machine, 

 reaching the conclusion that of the 50 H.P. 

 developed, 29 H.P. wiU be consumed in slip. 

 This is probably erroneous. If the cross sec- 

 tional area of the air-resisting parts be meas- 

 ured and proper coefficient applied it will be 

 found that they require a good deal more than 

 10 H.P. to overcome the resistance at 40 miles 

 an hour, and that the slip of the screw is much 

 less than estimated. 



Mr. Maxim has no good opinion of balloons. 

 He devotes a chapter to them, but expresses 

 the opinion that the day of the balloon is past, 

 evidently not recognizing the fact that the 

 flying machine, while capable of great speed, 

 is limited in size and carrying capacity by its 

 own increase of weight as the cube of its linear 

 dimensions, eventually reaching a size beyond 

 which it is no longer practicable, while the 

 balloon increases in surplus lifting power fas- 

 ter than its own weight and promises some 

 usefulness in spite of its inferior speed, its 

 bulk and its fragility. 



Mr. Maxim gives an account, all too brief, 

 of his own flying machine, weighing some 

 8,000 poimds, with 4,000 to 6,000 square feet 

 of sustaining surfaces, a motor of 363 H.P., 

 this being a steam engine of his own design 

 of unprecedented lightness, developing a thrust 

 at the screws of 2,164 pounds. This wonder- 

 ful and immense apparatus, the work of a 

 very able engineer, was run very many times 

 over a railway track of nine feet gauge, being 

 restrained from rising more than two feet by 

 guard rails of timber of thirty feet gauge. 

 With this arrangement many tests were made 

 and data obtained preliminary to an attempt 

 at free flight, but on July 31, 1894, the appa- 

 ratus rose with such force as to burst through 

 the guard rails and enter upon a cruise. 

 Steam was shut ofE at once and the machine, 

 after flying perhaps 200 feet, fell and was 

 broken. It was repaired, but various circum- 

 stances have prevented its being tested again. 



