332 SOME NEW BOOKS [april 



great gums, but surely no one has moralised on his feelings to such effect. " In 

 Middle Europe," says Semon, " the moon during the summer months stands 

 particularly low in the heavens, and remains but a short time visible. And 

 still this is the very season when the balmy night air suffers us to stay out-of- 

 doors to enjoy nocturnal scenery. In the tropics she stands nearly all night in 

 the zenith just above us. . . . The towering gum-trees stand white and shining 

 as if decked with silver, and almost without casting any shadow. Every line, 

 every leaf, shows distinctly, still the penetrating clearness of day is wanting, and 

 a mysterious veil lies over the shimmering landscape. Were I a poet I would 

 try to depict the impression of this sight in the human mind. Being a 

 naturalist, I feel the desire to analyse, and thus I ask myself : What is the 

 reason of this wonderful effect, this magic and mysterious element in the moon- 

 light landscape, which makes it an object of folk-lore and poet's fancy 1 ? The 

 answer to this question is near at hand. The effect of moonshine owes its 

 peculiar character to the circumstance of its giving light enough on clear nights 

 to illuminate a surface directly exposed to its rays. Thus, for instance, an 

 open book will be lighted up clearly enough to allow of your reading it. On 

 the other hand, however, it is not powerful enough to call forth a perceptible 

 brightness when diffused, i.e. indirectly reflected by the sky or the ground. To 

 this diffuse light we owe, however, the possibility of recognising in daytime 

 those parts of objects not directly exposed to the sun or even those that are 

 situated in the deepest shade. The blackness of the shadows in the height of 

 daytime is only a seeming one, brought about by contrast. . . . The contrary 

 is the case with moonlight. Here the diffuse reflected light is so weak as to 

 leave those parts of an object, which are not directly exposed to the rays, in 

 darkness, and make their details disappear to our sight. The chief character- 

 istic of moonlight thus consists less in the difference of its hue from that of 

 the sun — though this, too, strikes us in a peculiar way — than in the absence of 

 diffuse light and the almost absolute blackness of the shadows." 



All through the book one finds facts made the basis of reflections ; and this 

 undoubtedly adds much to the pleasure of the reader. But even when Semon 

 does not digress to philosophise about his facts, he manages to add to their 

 interest by his enthusiasm. No one will read unsympathetically his account of 

 his success with Geratodus. For long he searched in vain for the eggs of this 

 lung-fish; but one day Frank — the great good-for-nothing ! — came running to 

 the cam]}, "breathless and beaming with joy," thinking he had earned the 

 reward of £1 promised to him who should first find the spawn. But Frank had 

 not got the right thing, and it was about six weeks later that the "glorious 

 discovery " was made. Semon tells of his troubles with the blacks, of difficulties 

 in pickling the eggs and rearing the young fish : we mourn with him over some 

 that were done to death by the excessive kindness of a girl-friend. 



The later chapters of the book, relating to regions in which Semon stayed 

 only a short time, are less satisfying than the earlier ones ; but on the whole 

 the work is to be recommended as full of interesting facts that are well told. 



Gregg Wilson. 



THE LIVES OF STREAMS 



Eiver Development, as illustrated by the Rivers of North America. By 

 Professor I. C. Russell. 8vo, pp. xvi. + 327, with 23 figures and maps. 

 London: John Murray, 1898. Price 6s. 



This is a very useful work on an interesting subject ; yet there remains the 

 feeling that it might have been better. A little more systematic arrangement 

 might have been accomplished ; there would have been avoided some repetition, 

 and such a divorce as to separate ' the migration of divides ' from ' stream 

 conquest.' 



