April 13, 191 1] 



NATURE 



229 



cause of an actual increase in the amount of protein 

 absorbed, and has shown that some improvement in con- 

 dition attends this alteration. His work promises, there- 

 fore, to be in a very real sense of economical value to the 

 Government, indicating a better maintenance of health on 

 wisely diminished rations. This statement also applies to 

 his study of the salt requirements of these diets, which lead 

 him to the conclusion that more salt is supplied than is 

 useful, and that the excess is detrimental. 



The author has carefully studied changes following an 

 increased absorption of protein from the diet, and presents 

 an admirable case for discussion alongside the valued 

 contributions of Chittenden. He has enlarged his presenta- 

 tion of this case by reference to the habits of the different 

 native races within his view. According to him, these 

 races may be arranged in a series, in which virile character- 

 istics vary directly with the protein value of the diet, and 

 are greatest where, as amongst flesh-eaters, this value is 

 at a maximum. Carnivorous man sets to his work with 

 zest, and is prepared to labour strenuously, and, if need 

 arise, fight for life. The vegetarian spends a gloomy exist- 

 ence, embarrassed by an internal tangle of cellulose, and 

 is swept off by feebly resisted disease. Some of the 

 evidence offered in support of this contention is not of the 

 same value as that in the remainder of the report, but it 

 is highly interesting, and has been usefully published. 



Prof. McCay is to be congratulated upon a report that 

 should be found in every library of physiological literature. 

 The opportunities provided by such a systematic observa- 

 tion of human beings under very precise control are great, 

 and have been well utilised. 



J. S. Macdonald. 



RECENT PROGRESS IN AERONA UTICS> 

 nPHE sudden development of the art of flying which has 

 -*■ come upon the world during the last few years may 

 be classed as one of the most extraordinary events in the 

 world's history. We have had far-reaching inventions 

 introduced before, such as the railway, the telegraph, the 

 telephone, the motor-car, and many others, but all these 

 have gradually developed, have sprung from small 

 beginnings, and often it seemed doubtful whether they 

 "• 'lid ever develop into utility of real importance. With 

 llying machine it is different. True it is that the 

 lit of such an apparatus has been foreseen, not merely 

 -ome years, but for centuries. The inception is very 

 Like the sailor's story to his incredulous grandmother 

 le flying-fish, so a hundred years ago no one would 

 been dumbfounded if one had prophesied that men 

 .<\ fly, although one would have been accused of talk- 

 nonsense had one foretold that we could talk along a 

 hundreds of miles long, see bullets embedded in the 

 >, or be able to reproduce a song sung by one departed, 

 dare not at present hazard a guess as to what the 

 L;-machine may eventually develop into. There are 

 those who think it will never be much more than a 

 I losity, but there are others who believe it will soon 

 Ii' ■ 'line our usual mode of travel, and that railways, steam- 

 boats, and motor-cars will have to take quite a back place 

 n comparison. 

 My object to-night is not to give a full history of the 

 .vigation of the air. That is getting into a big subject 

 t would occupy a long time to properly relate. Nor is 

 s to be a very technical lecture ; I propose now merely 

 refer to the latest developments — to trace some lines of 

 lUght which I hope may serve as a basis on which my 

 rers may build more solid structures for the improve- 

 nt of the navigation of the air. 

 jAerial machines have been classed under two headings, 

 ■wn as lighter-than-air and heavier-than-air. I do not 

 rpose going very deeply into the question of the first 

 lass, because I am inclined to think it is a subject of 

 !Omparatively little importance, the latter having made 

 juch very much greater progress of late, and being able 

 :o effect almost all that the dirigible is designed to do and 

 with greater ease and efficiency, that it seems likely to 

 ntirely oust the former. 

 A few words, however, on gas-borne vessels may be 



1 P.nper read before the Junior Institution of Engineers on April ii, 

 ly Major B. Baden-Powell. 



I NO. 2163, VOL. 86] 



desirable to point out how they have been evolved, and in 

 which direction improvements may be looked for, should 

 their development be considered advantageous. 

 Balloons. 



First we have to consider that simple contrivance the 

 balloon, by means of which men have, for the lasi century 

 and a quarter, been able to rise in the atmosphere and 

 drift with the wind wheresoever it listeth. It is a remark- 

 able fact that, notwithstanding the great hopes it raised 

 in early days, scarcely any improvement has been made in 

 this contrivance during a hundred years of practice. This 

 refers to the simple balloon. Almost immediately after its 

 invention suggestions were made to form it as a long 

 vessel and propel it with screws, and though to-day we 

 have the practicable dirigible balloon, it is probable that 

 no invention has been longer in developing. Step by step 

 it has grown from the ideas of Meusnier, through the 

 crude machines of Giffard, de L6me, Tissandier, to the 

 first successful vessel, that designed by Colonel Renard, 

 nearly thirty years ago. Though much progress has been 

 made since, it has always been slow. 



Santos Dumont evoked much public interest with his 

 little vessels ; Count Zeppelin certainly made a big step 

 forward with his large rigid-framed leviathans, while 

 Parseval, Gross, Julliot, and others have further developed 

 the invention. From Giffard's steam engine of 3 horse- 

 power to the 500-horse motor of the Siemens-Schuckert, 

 every variety of engine has been tried, continually 

 increasing in power. 



Nor does it appear that any very revolutionary advance- 

 ment is likely to be effected in the future with dirigibles. 

 We may hope to go on making each vessel a little better 

 than the last, much in the way in which steamships have 

 progressed. 



Undoubtedly the main path along which improvement is 

 {K>ssible and desirable is that of speed. So long as an 

 aefial machine is only able to progress at a rate not much 

 above that at which the wind usually blows, it is bound 

 to be very dependent on the ever changeful weather. .'\ 

 dirigible can never be considered really practical (in this 

 country at least) until it is capable of travelling at, say, 

 40 miles an hour. This is a speed not yet attained by 

 any dirigible. The wind at one or two thousand feet up 

 frequently blows at 30 miles an hour, and not only must 

 we be able to make head against this, but we ought to be 

 able to progress fully 10 to 20 miles in the teeth of it. 

 Now, considering for the moment solely the lighter-than- 

 air machine, given a certain weight of engines, since 

 buoyancy is dependent on displacement, we cannot make 

 the vessel any smaller if it is to lift the weight. In order 

 to increase its speed, then, presuming the shape and the 

 surface and fittings to be such as to offer a minimum of 

 resistance, there seem but two possible means. One is to 

 make engines more powerful for their weight, and progress 

 in this line seems moving rapidly. The other is to in- 

 crease the size of the gas-holder. .As the volume is 

 enlarged the lifting power (and hence ability to carry more 

 powerful engines) is increased at a greater rate than is 

 the cross-section and surface, and consequent resistance. 

 So we get the tendency to construct huge machines ever 

 growing larger. This size, however, is one of the greatest 

 practical drawbacks to the employment of such vessels. 

 It is true there is plenty of room in the sky, and if the 

 machines had to remain always aloft there might be no 

 difficulty. But to be of use they must come to earth, and 

 the enormous bulk has to be held stationary against any 

 wind that may happen to blow. This is exceedingly 

 difficult, and necessitates the use of sheltered harbours and 

 sheds to house these monstrous structures, which implies 

 vast expense. 



There is, however, yet another means by which it may 

 be possible to increase the speed without adding to the 

 bulk. It is one that has often been suggested, several 

 times tried on a large scale, but does not seem to show 

 signs of general application. I refer to the use of hori- 

 zontallv disposed surfaces known as aeroplanes. If we 

 have an apparatus travelling at, say, 30 miles an hour, and 

 we add such devices, it will be found that they give a 

 verv considerable extra lift, and this may be utilised for 

 raising an extra weight of engines. By adding to the 

 propulsive power we both increase the speed, aiiA theroby 



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