1897] SOME NEW BOOKS 343 



25 lbs., so that experiments with it were easier and much less 

 costly. 



Mr Langley has shown, then, that flying machines can be made 

 which will rise in the air, fly for a short time, and descend without 

 mishap. But before the problem of flight is solved many difficulties 

 must be got over, the difficulties of (1) launching without any 

 elaborate apparatus ; (2) maintaining equilibrium in gusty winds ; (3) 

 carrying sufficient fuel for long flights ; (4) alighting safely even when 

 the circumstances are not specially favourable. An oil engine is now 

 being made to be affixed to the gliding machine. As an aeronaut will 

 be on board, a distinct advance on Mr Langley's aerodrome, which had 

 no living pilot, is contemplated. 



The article on sailing flight by Mr Chanute reviews the various 

 theories on the subject judiciously. There is no doubt, as he says, 

 that in very many cases birds soar by the help of ascending currents 

 of air. But it is probable that sometimes when there is no such 

 current available, they nevertheless succeed in rising without a beat of 

 their wings. Over level ground in Egypt, covered with green crops, 

 where great heating or unequal heating of the surface seemed out of 

 the question, so that there was nothing to start an upward current, 

 the present writer has seen kites soaring with perfect ease. 



Mr Chanute thinks that birds can soar by the help of a ' nearly 

 uniform ' horizontal breeze, but happily he does not, in contempt of 

 dynamics, hold that an absolutely uniform horizontal breeze can lift 

 them. He makes some good remarks on the question why some birds 

 frequently soar, whereas others, and among them very good flyers, 

 never do. He thinks that soaring depends on the arching of the 

 wing, and it is quite possible that this may be the case. In the rapid 

 pulsations of ' rowing ' flight the front margin of the wing does the 

 main work. In the stately gyrations of the soaring adjutant it is 

 probable that the ample concavity is of more service. But far more 

 cross-sections of wings than he gives are wanted before it is possible 

 to accept this explanation, and in particular small birds should be 

 well illustrated. It is remarkable that no bird so small as a thrush 

 ever soars. 



The subject of flight does not so often as formerly give rise to 

 utterly wild theories. The Annual as a whole is remarkably free from 

 wild writing. But the old tendency shows itself in Mr Huffaker's 

 theory that a bird in soaring causes a down-current, which in turn 

 starts an up-current, which supports him as he rises ! 



F. W. Headley. 



Contemporary Psychology 



The Psychology of the Emotions. By Th. Ribot. 8vo, pp. xix + 455. London: 

 Walter Scott (Contemp. Sci. Ser.), 1897. Price, 6s. 



The New Psychology. By E. W. Scripture. 8vo, pp. xxiv + 500. London: 

 Walter Scott (Contemp. Sci. Ser.), 1897. Price, 6s. 



These two volumes of the Contemporary Science Series exhibit 

 Psychology in very different aspects. Prof. Eibot's work on the 

 emotions is characterised by breadth of view, wide range of know- 

 ledge, admirable lucidity of presentation, bold and yet critical use of 



