August 21, 1890] 



NATURE 



389 



The result of this systematic and laborious task of 

 gathering all these records and observations reflects great 

 credit on the editor, who seems to have spared no pains 

 to insure the accuracy of the information recorded. 



Photogravure. By W. T. Wilkinson. (London : Ilifife 

 and Son, 1890.) 



The aim of photographers has long been to produce 

 prints, permanent and artistic in effect, with the delicacy 

 and truthfulness of a photograph from nature. The process 

 •of photogravure seems to fulfil these requirements, and 

 for purposes of book illustration should form a most im- 

 portant factor from the commercial point of view. The 

 process is both simple and interesting, and requires little 

 apparatus or material which is not already found even 

 in most amateur's photographic dark rooms. 



Mr. Wilkinson describes in this little book a method 

 employed in obtaining a finished plate, the process being 

 divided into six stages. The first is the production of a 

 transparency upon a special (transparency) carbon tissue 

 from the negative ; in the second, from the transparency 

 a negative in ordinary carbon tissue is made ; the third 

 consists in laying the etching ground upon a polished 

 copper plate ; in the fourth the carbon image (second 

 stage) is mounted and developed upon the prepared 

 copper plate ; the fifth stage deals with the protection of 

 the margin, and etching and burnishing ; and the sixth 

 and last stage gives us the print from the plate, done in 

 much the same manner as copper-plate etchings and 

 jnezzotint engravings. The frontispiece, by W. L. Colls, 

 affords a good illustration of a result of this process. 



Elements of Euclid, Book I. By Horace Deighton, 

 M.A. New Edition, Revised. (London : George Bell 

 and Sons, 1890,) 



The present edition of Mr. Deighton's book is a great 

 improvement on many of the works on this subject. In 

 addition to the ordinary propositions, the solutions of a 

 large number of important propositions are incorporated 

 in the text with riders attached to them, which will be 

 found useful, since in examinations nowadays more is 

 required than is contained in Euclid. 



Abbreviations and other symbols are used throughout, 

 with the exception of the first fifteen propositions, and 

 great clearness is obtained in the propositions and 

 problems by making the construction lines thin, and also 

 by printing the letters referring to the figures in a larger 

 and more conspicuous type. 



At the end of Book L a series of examples is given on 

 the propositions in it, and a short chapter on plane loci is 

 added. This book will be especially instructive to 

 beginners, the author having smoothed the path for 

 those who wish to acquire facility in solving geometrical 

 questions. 



Camping Voyages on German Rivers. By Arthur A. 



Macdonell. (London: Edward Stanford,' 1890.) 

 In this book Mr. Macdonell gives an account of boating 

 expeditions on German rivers. Some of the streams he 

 describes have already been dealt with in English books, 

 but he may fairly claim that no previous work of the kind 

 is so nearly complete as his own. Every German river — 

 with the exception of the Lahn — which an Englishman 

 would care to see, he has navigated ; and his experiences 

 with regard to each are carefully recorded. We need 

 scarcely say that for young and vigorous travellers there 

 is no more delightful way of visiting a beautiful country. 

 It not only provides them with healthy physical exercise, 

 but takes them into the midst of enchanting scenery, and 

 gives them opportunities of becoming intimately ac- 

 quainted with interesting towns and villages. Mr. Mac- 

 donell has thoroughly appreciated the happiness which 

 lias thus come in his way ; and in this book he contrives 

 to communicate to his readers a good deal of the pleasure 



NO. IO?6, VOL. 42] 



with which he recalls his adventures, and depicts what he 

 has seen. The work is based on notes taken down each 

 day in the course of the various voyages, and to some ex- 

 tent this no doubt accounts for the brightness and fresh- 

 ness of the narative. The value of the book is much 

 increased by good maps, of which no fewer than twenty 

 are given. 



Epping Forest. By E. N. Buxton. Third Edition. 



(London : Edward Stanford, 1890.) 

 We are glad to welcome a new edition of this excellent 

 little Guide. Mr. Buxton says the idea of writing it oc- 

 curred to him when he observed how small a percentage 

 of the summer visitors to Epping Forest ever ventured 

 far from the point at which they were set down by train 

 or vehicle. No one to whom this Guide is known will be 

 content to go to Epping Forest without trying to see as 

 much of it as can be conveniently visited. Mr. Buxton 

 has lived all his life in one or other of the Forest 

 parishes, and knows exactly what parts of the subject 

 are most worthy of being fully dealt with. He knows 

 also how to express concisely and clearly all that he 

 wishes to say. For visitors who are interested in natural 

 history he has added some chapters on " the different 

 forms of life which they may expect to find in the course 

 of their rambles." 



LETTERS TO THE EDITOR. 



[ The Editor does not hold himself responsible for opinions ex- 

 pressed by his correspondents. Neither can he undertake 

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

 manuscripts intended for this or any other part of Nature. 

 No notice is taken of anonymous communications. ] 



The "Barking Sands" of the Hawaiian Islands. 



About a year ago Nature printed my letter from Cairo 

 giving a condensed account of an examination of the Mountain of 

 the Bell {Jebel Nagous) on the Gulf of Suez, and of the acoustic 

 phenomenon from which it is named. In continuation of my 

 researches on sonorous sand, which are conducted jointly with 

 Dr. Alexis A. Julien, of New York, I have now visited the so- 

 called "barking sands " on the island of Kauai. These are 

 mentioned in the works of several travellers (Bates, Frink, Bird, 

 Nordhoff, and others), and have a world-wide fame as a natural 

 curiosity ; but the printed accounts are rather meagre in details 

 and show their authors to have been unacquainted with similar • 

 phenomena elsewhere. 



On the south coast of Kauai, in the district of Mana, sand- 

 dunes attaining a height of over one hundred feet extend for a 

 mile or more nearly parallel to the sea, and cover hundreds of 

 acres with the water-worn and wind-blown fragments of shells 

 and coral. The dunes are terminated on the west by bold cliffs 

 [Pali) whose base is washed by the sea ; at the east end the 

 range terminates in a dune more symmetrical in shape than the 

 majority, having on the land side the appearance of a broadened 

 truncated cone. The sands on the top and on the landward 

 slope of this dune (being about 100 yards from the sea) possess 

 remarkable acoustic properties, likened to the bark ot a dog. 

 The dune has a maximum height of lo8 feet, but the slope of 

 sonorous sand is only 60 feet above the level field on which it is 

 encroaching. At its steepest part, the angle being quite uni- 

 formly 31°, the sand has a notable mobility when perfectly dry, 

 and on disturbing its equilibrium, it rolls in wavelets down the 

 incline, emitting at the same time a deep bass note of a tremu- 

 lous character. My companion thought the sound resembled 

 the hum of a buzz saw in a planing mill. A vibration is some- 

 times perceived in the hands or feet of the person moving the 

 sand. The magnitude of the sound is dependent upon the 

 quantity of sand moved, and probably to a certain extent 

 upon the temperature. The drier the sand the greater the amount 

 possessing mobility, and the louder the sound. At the time of 

 my visit the sand was dry to the depth of four or five inches ; its 

 temperature three inches beneath the surface was 87° F., that of 

 the air being 83° in the shade (4.30 p.m.). 



When a large mass of sand was moved downward I heard the 

 sound at a distance of 105 feet from the base, a light wind 



