May 23, 1889] 



NATURE 



77 



information ; so many travellers have lately recorded their 

 impressions of Japan that it would now be hard for a 

 writer to present any part of the subject from a wholly 

 new point of view. Nevertheless, Mr. Dickson's book is one 

 of exceptional interest, for, having already been in Japan, 

 and having carefully studied its history, he knew exactly, 

 on his return, the kind of phenomena which it would be 

 best for him to study. Accordingly, we find in his narra- 

 tive that he fastens attention chiefly on what is really 

 characteristic of Japanese life, and that he understands 

 how to connect particular facts with the general ten- 

 dencies of Japanese society. Mr. Dickson was, of course, 

 greatly struck by the enormous changes which had taken 

 place from the time when he had formerly visited Japan, 

 and he adds largely to the value of his observations by 

 steadily comparing and contrasting the conditions which 

 came under his notice four or five years ago with those he 

 had noted twenty years before. About Japanese customs 

 and institutions, so far as they are of native origin, he 

 writes in a kindly and appreciative spirit ; and he also 

 finds something to admire in the effort of the educated 

 classes " to advance in Western learning and the acqui- 

 sition of scientific information." He declines, however, to 

 commit himself to any very decided opinion as to the 

 future of Japan. That she may have serious troubles in 

 store for her he does not dispute ; but, if they come, they 

 will, he thinks, spring altogether from internal causes, and 

 he has sufficient respect for her rulers to suggest that 

 they " may have wisdom to avert a crash." 



Statics for Beginners. By John Greaves, M.A. (London : 

 Macmillan and Co., 1889.) 



To simplify the subject of statics, and to make it attractive 

 at the sam'? time, is by no means an eisy task, but the 

 author of this little book has gone far towards succeeding 

 in doing this. With the approval of several experienced 

 teachers, the principle of the transmissibility of force has 

 been discarded in favour of the ordinary method. The 

 parallelogram of forces is deduced from the laws of 

 motion, Duchayla's proof being given as an alternative. 

 The definitions are admirable, and the various proofs are 

 as simple as they well can be. 



The examples are progressive and very numerous, 

 typical ones being fully wor!;ed out. 



The book is admirably adapted to serve as a stepping- 

 stone to the larger treatises. 



LETTERS TO THE EDITOR. 



[ Th4 Editor does not hold himself responsible for opitiions ex- 

 pressed by his correspondents . Neither can he undertake 

 to return, or to correspond with the ivriters of, rejected 

 manuscripts intended for this or any other part of NATURE. 

 No notice is taken of anonymous communications.'\ 



The Structure and Distribution of Coral Reefs. 



As I have had no personal experience of coral-reefs, I do not 

 wish to touch more than the literary side of the controversy, 

 but, in regard to this, Mr. Guppy's letter in the last number of 

 Nature (p. 53) obliges me to call attention to the fact that 

 the "90-fathom reef" which he mentions is not at Socotra, but 

 at Rodriguez. Also that, apart from Mr. Guppy, I found little 

 evidence of "ignorance of the depths in which coral-reefs may 

 form." On the contrary, there appeared to be a remarkable 

 concurrence of testimony on the part of observers that, though 

 occasionally a reef-building species may be found alive at depths 

 greater than about 25 fathoms, this bathymetric limit for the 

 growth of reefs, assigned by the earlier observers, is sufficiently 

 accurate for all practical purposes. 



It seems, then, to me that, with the evidence before us, the 

 onus probandi of the supposition that a reef may commence at 

 any depth which the exigencies of a particular case require, 

 rests on Mr. Guppy (this done, no theory of coral-reef forma- 

 tion is needed — they may grow anywhere). But, till he can 

 establish this hypothetical but fundamental proposition, Masa- 

 marhu Island is a fact for Darwin. T. G. BoNNEY. 



The Turtle-headed Ro;k Cod. 



A RARE specimen of the turtle-headed rock cod {Glyptauchen 

 panduratus) has just come into the hands of Mr. J. Douglas 

 Ogilby, of the Ichthyological Department of the Australian 

 Museum at Sydney. This extraordinary fish belongs to the 

 family of the red rock cods. Not many years ago these fishes 

 (the red rock cod and its allies) formed a part of a most miscel- 

 laneous c:>nection of species, which, under the general title of 

 Triglidce, included the true gurnards {Tngla and I.epidotrigla), 

 the flying gurnards {Dactylopterus), Siwi the flat- heads {Platy- 

 cephalus). In i860, however, Dr. Giinther wisely separated 

 these fishes from the Triglidic, which family he broke up into 

 four distinct groups. The first of these, named by him Scorpce- 

 nidiE, is that to which the specimen just captured at .Sydney 

 belongs. All the Scorp,cnidiC are carnivorous marine fishes, most 

 of which live at the bottom of the sea, and are generally provided 

 with a powerful armature of the head and fin spines ; while many 

 possess skinny appendages on the head and body variously de- 

 veloped, which, owing to their resemblance to the fronds of sea- 

 weeds, serve the double purpose of enabling them the more easily 

 to obtain their food, and the more effectually to conceal them- 

 selves from their enemies. As they are mostly of a small size, 

 this latter point is evidently of no slight value, because, being 

 slow, lazy fishes, they would, without some such means of pro- 

 tection, be unable to cope with their swifter antagonists. Nature 

 has additionally protected this family by enabling it to vary its 

 coloration according to any change of locality which it may be 

 necessary to make, so as, chameleon-like, to fit itself for adapta- 

 tion to the various phases of life under which it maybe called on 

 to exist. The genus Glyplawhen, of which the species just 

 received by Mr. Ogilhy is the sole representative, was separated 

 in i860 by Dr. A. Giinther from the Cuvierian genus Apistus, 

 for the reception of a fish from King George's Sound, Western 

 Australia, described many years ago by Sir John Richardson 

 under the name o^ A. panduratus. It has since been recorded 

 from Port Jackson (Sydney), and the present specimen comes 

 from Manly Beach, a few miles to the north of Port Jackson. 



T. 



Atmospheric Electricity. 



Your correspondent, Mr. C. A. C. Bowlker, will, probably, 

 be interested to learn that an electrical discharge, exactly similar 

 to that which he recently experienced on the Glydyr Fawr 

 (? " Elidyr") was described by the late Dr. Mann, and by Mr. 

 F. G. Smith, in the Quarterly Journal of the Meteorological 

 Society for October 1875. 



Mr. Smith was engaged in August 1865 in a cending the Lin- 

 guard Mountain from Pontresina, when his party was overtaken 

 by bad weather. They reached the summit, however, and found, 

 at one end of the ridge of which it consists, a fl ig-staff tipped 

 with an iron point, and, at the other, a flat metal disk, serving 

 to indicate bearings. Snow was falling, and nothing was visible 

 except mist, but the "otherwise death-like stillness of the spot 

 was broken by a strange, intermittent noise, resembling the 

 rattling of hailstones against the panes of a window. A careful 

 investigation of the cause of this noise soon made it apparent 

 that it proceeded from the flag staff, and was due to the passage 

 of a continuous electrical discharge from the cloud in which the 

 summit was wrapped." 



After a time, the party, although, by Mr. Smith's own 

 admission, "alarmed," held their alpenstocks, points up- 

 ward, in the air, and, at once, each became conscious of 

 an "electrical discharge passing through him, and causing a 

 throbbing in the temples and a tingling in the linger-ends. The 

 noise was still vigorously proceeding when, after three-quarters 

 of an hour's stay, Mr. Smith and his party left the summit." 



I called attention to a somewhat similar phenomenon ("An 

 Engineer's Holiday," vol. i. p. 204), which I experience;! on 

 crossing the divide separating Central City from Idaho 

 Springs, Colorado, the height of the ridge being 10,000 feet 

 above sea-level. 



There was thunder, and "it was raining, but without 

 lightning, as we neared the divide, when 1 felt a tickling 

 sensation on the backs of my hands. Presuming that a dis- 

 charge was taking place between our bodies and the cloud, I 

 tried to increase its intensity by holding my wet umbrella, point 

 upwards, above the waggon. This, at once, produced distinct 

 sensations in the hand and arm, the driver reirarking, ' (Jh ! 

 that's common enough here, though many don't know what it is, 



