March i6, 1905J 



NA TURE 



463 



tools and jade ornaments, knives, hatchets, arrow- 

 heads, armlets, rings, and a multitude of stone seats 

 and idols. 



Let us hope that Mr. Hartman may follow up his 

 good and useful work by an exploration of the north- 

 western slope of the country which has been the 

 scene of his labours. George Earl Church. 



PROGRESS IN AERIAL NAVIGATION. 



THE problem of aerial navigation has been 

 attacked bv direct methods for so many 

 centuries that the results of the recent aeronautical 

 competition at St. Louis can scarcely be regarded as 

 a matter of surprise. It is doubtful whether the 

 offering of large prizes for the achievement of a 

 result which has been attempted for years without 

 success is the best means of promoting progress. 

 As will have been learnt from the daily Press the 

 great prize of 20,000?. was not even competed for, 

 and a much more useful purpose would have been 

 served by a systematic and organised attempt to 

 encourage, by means of prizes, investigations 

 calculated to throw an indirect light on the general 

 question of aerial navigation, such, for example, as 

 improvements in the efficiency of propellers, diminu- 

 tion of the angle of gliding of gravity-propelled 

 machines, reduction of air-resistance of motor-pro- 

 pelled balloons, solution of the difficulties connected 

 with longitudinal stability, especially in gliding 

 machines travelling at low speeds, and what is still 

 more important, the discovery of new results in any 

 direction whatever calculated to open up fresh 

 methods of approaching the whole question. 



If we chronicle merely the attempts that have 

 successfully been made in striking out on new lines, 

 leaving out of account improvements subsequently 

 made on the same lines, and also omitting early 

 attempts such as those of Dante of Perugia and Le 

 Bris, a history of aerial navigation will be summed 

 up in the following short list : — (i) Montgolfier's dis- 

 covery of the balloon ; (2) application of mechanical 

 power to the propulsion of balloons by Renard and 

 Ivrebs ; (3) introduction of gliding experiments under 

 gravity by Lilienthal ; (4) the introduction of explo- 

 sion engines and other light motors theoretically 

 capable of maintaining a flying machine in the air. 

 I^ach of these innovations has brought the goal more 

 distinctly in view, and yet experiments so far have 

 left a wide gap between the results of actual per- 

 formance and what is necessary to render aerial 

 navigation practically useful. The special difficulty 

 connected with aerial navigation is that it is not 

 easy to see how to approach the problem except by 

 direct methods of attack, while the great majority 

 of scientific discoveries have been made indirectly as 

 the result of observations originally undertaken for 

 some entirely different object that has been known 

 from the very outset to be possible of attainment. 



By analogy with fishes and birds, respectively, the 

 two forms of machine experimented on, involving as 

 they do the use of gas bags and aeroplanes or aero- 

 curves, might not inappropriately be described as the 

 aerial swimming machine and the flying machine 

 proper. It is somewhat remarkable in the face of 

 natural evidence that the swimming machine has up 

 to the present proved by far the "most tractable of 

 the two, and has undoubtedly led to the best results. 

 It is the safest to experiment with. That accidents 

 have frequently occurred is perfectly true, but thev 

 have all been attributable to causes' not beyond the 

 ken of an ordinary practical but intelligent mechanic. 



Of aerial swimmers constructed within the last few- 

 years the most notable ones an- undoubtedlv the 

 NO. 1846, VOL. 7 l] 



Santos Dumont series, the ill-fated De Bradski air- 

 ship, the Lebaudy, Barton, Spencer, Baldwin, Ben- 

 bow, Beedle, and Deutsch forms. A few details of 

 these, collected for comparison, may be of interest. 



M. Santos Dumont's No. 7 is 160 feet long and 

 23 feet in diameter, and is provided with a four-cylinder 

 motor capable of developing 60 horse-power and 

 making 1200 revolutions per minute. Its prede- 

 cessor, No. 6, was 108 feet long and 20 feet in 

 diameter, with a motor of 16-20 horse-power. This 

 was the machine which won the Deutsch prize, and 

 its speed relative to the air was probably about 19 

 miles an hour. No. 7 was originally intended to 

 compete at St. Louis, but M. Santos Dumont did not 

 enter. 



The De Bradski airship is now a thing of the 

 past. It was III feet long and weighed about 

 19231b., and a special feature was that the machine 

 was not quite light enough to raise itself, the ascent 

 being effected by a screw revolving in a horizontal 

 plane. The experiment ended in October, 1902, with 

 a fatal accident, the airship becoming unmanage- 

 able, and the car breaking away owing to the weak- 

 ness of its supporting wires. 



The experiments of MM. Lebaudy have been 

 remarkably successful in spite of an accident which 

 destroyed their first machine in November, 1903. 

 This did not deter these indefatigable aeronauts from 

 constructing, partly out of the wreckage of the old 

 one, a new machine of the following dimensions : — 

 Length 58 metres, greatest diameter 9.8 metres, 

 volume of gas 2600 cubic metres, or about 94,000 cubic 

 feet ; motor, a four-cylinder Daimler of 40 horse-power 

 running at 250 to 1200 revolutions per minute; pro- 

 pellers, two screws 2 44 metres in diameter running 

 at 800 to 1000 revolutions per minute. Of the thirty 

 voyages made with this " aerial cruiser " in 1904, the 

 following appear to have been the most successful : — 

 .August 16, a distance of :6 miles in 41 minutes; 

 November 22, a run of i hour 33 minutes. An 

 accident occurred on .August 28 owing to the 

 " swimmer " breaking loose, but it floated away to 

 a distance and finally got caught in a wood 70 

 kilometres distant, whence it was brought back with 

 slight damage. The present model is remarkably 

 like a fish in shape, and the resemblance is further 

 accentuated by the tail-like double horizontal rudder 

 in the stern. The balloon has a flat base with a 

 long vertical keel, and all these arrangements are 

 well calculated to make it travel steadily. 



Beyond the mere rumour of an accident last spring 

 the Barton airship seems to have lapsed into oblivion 

 of late, but it must not be forgotten that a year is .• 

 small interval of time in the construction of aero- 

 nautical machines. The dimensions given are as 

 follows : — Length of balloon 170 feet, diameter 

 40 feet, total estimated weight 15,7001b. ; number of 

 propellers, six, each consisting of six blades arranged 

 tandem fashion, placed in pairs, one on each 

 side of each motor ; motors, three in number, develop- 

 ing 50 horse-power each, and running at 1600 revolu- 

 tions. A peculiarity of Dr. Barton's design is the 

 series of aeroplanes, thirty in number, employed to 

 raise the machine. The shape of the balloon and 

 the structure of the underlying framework and car 

 suggest the possibility of considerable head resist- 

 ance. 



Of the performances of Messrs. Spencer's air- 

 ship satisfactory records were given in the Press at 

 the time. The dimensions are : — Length 93 feet, 

 diameter 24 feet; propeller, a single screw 12 feet in 

 diameter, placed in front; engine of 24 horse-power 

 running at 1050 revolutions. 



Mr. Baldwin's and Mr. Benbow's airships, ex- 

 hibited at .St. Louis, appear not to have made any 



