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 PsycHoLocy oF THE Emotions. By Th. Ribot. 8vo, pp. xix+455. London: 
Walter Scott (Contemp. Sci. Ser.), 1897. Price, 6s. 
Tue New Psycuotocy: 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. Ribot’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 
