46 



NATURE 



\May 20, 1875 



the coral reef at Upware, and the Kimmeridge clay at Ely, 

 We have next a discussion of the coprolite and associated 

 beds at Potton and Upware, which Mr. Bonney considers 

 Upper Neocomian,and hethinks most of the fossils derived. 

 After a short notice of the Gault comes a full discussion 

 of the interesting questions connected with the so-called 

 Upper Greensand. An admirable outline of its palaeon- 

 tology is first given, and the origin of its phosphatic 

 nodules is then concluded to be analogous to that of flint, 

 or what is here called concretionary action. With regard 

 to its age, Mr. Bonney follows Mr. Jukes-Browne in con- 

 sidering it homotaxial with the chloritic marl, and a large 

 part of its fossils derived from the Upper Gault. The 

 chalk is dismissed with a very short notice, and an 

 account of the Post Pliocene deposits concludes the 

 sketch. These deposits are described under six divisions, 

 the lowest being the true Boulder Clay. The most in- 

 teresting of these is the " Fine Gravel of the Plains," 

 which has yielded so many mammalian remains. Five 

 appendices follow : on Upware sections, the Ely pit, the 

 Hunstanton red rock, the water supply, and building 

 stones of Cambridge. The second of these might well have 

 been omitted, for though it refers to an interesting case of 

 a large chalk boulder, we are no\Y sufficiently familiar 

 with such instances of huge transported rocks to make it 

 waste of time to discuss imaginary systems of impossible 

 faults to account for its presence in some other way. 



'Journey across the Western Interior of Australia. By 

 Col. Peter Egerton Warburton, C.M.G. With an In- 

 troduction and Additions by Charles H. Eden. Edited 

 by H. W. Bates. With Illustrations and a Map. 

 (London : Sampson Low and Co., 1875.) 



Col. Warburton well deserves any honours which he 

 may have received ; for the sake of increasing knowledge 

 he has performed as bold a feat of travel as is on record. 

 With his son, Mr. J. W. Lewis, two Afghan camel-drivers, 

 and two natives, he set out on April 15, 1873, from Alice 

 Springs, in E. long. 133° 53' 14", S. lat. 23° 40', about 

 1,120 miles north from Adelaide, and travelled right across 

 the centre of the Australian continent, reaching the 

 western side in January 1874. Col. Warburton's narrative 

 in the book before us consists of the record which he kept 

 day by day of his progress. The party had sixteen camels, 

 and were provisioned for six months. Experience has 

 shown that to explore Central Australia camels alone are 

 of any use, horses being totally unable to bear up against 

 the universal scarcity of water, and the bristling spinifex 

 stalks which cover the ground almost everywhere, and 

 which cut their legs to pieces. Col. Warburton's journal, 

 not long after the start, becomes a painful record of a 

 daily hunt after water, a hunt which was often unsuccess- 

 ful. During the greater part of the journey man and 

 beast were in a chronic state of parching thirst. The 

 country crossed over is as arid and desolate a wilderness 

 as can well be conceived, consisting mainly of low sandy 

 hills covered almost everywhere with the above-mentioned 

 spinifex, occasionally varied by a salt marsh, a few hills, 

 and rarely a few trees. Indeed, the whole country from 

 121° to 131° E. long, is one great sandy desert. Bustards, 

 one or two species of pigeons, owls, rats, a small species 

 of kangaroo, swarms of torturing flies and ants, were 

 met with, the last-mentioned with painful frequency. 

 Natives were also seen, and they proved perfectly harm- 

 less and generally shy, and some of them Col. Warburton 

 describes as handsome and well made. 



The general method of procuring water was to scoop 

 out wells in the sand, and it was only at long intervals 

 that suitable places occurred. The food supplies of the 

 party were very soon exhausted, and they had for the 

 greater part of the journey to live on roots, an occa- 

 sional " wallaby " (small species of kangaroo), and on the 

 camels which they were compelled to kill. Of the four- 

 teen camels, only two reached the journey's end, some 



having been lost, some left behind as unable to move, and 

 seven killed for food. The flesh of the latter seems to 

 have t een as tough and devoid of nourishment as leather, 

 and by the time the party reached the welcome river 

 Oakover they were all nearly on the point of starvation ; 

 latterly. Col. Warburton himself had to be tied on his 

 camel's back. On reaching the Oakover, some of the 

 party pushed on to the settlement for relief, which at last 

 came, and Col. Warburton met with an enthusiastic 

 reception everywhere from Roeburne to Perth and on to 

 Adelaide. He has made a valuable contribution to our 

 knowledge of Central Australia, and as the spirit of ex- 

 ploration seems to be thoroughly aroused in the colony, 

 we may hope soon to have its geography at last filled up. 

 The difficulties and dangers of Australian exploration are 

 well known, and by forethought and organisation no 

 doubt they might be successfully met. It seems doubtful 

 whether any economic use can ever be made of the arid 

 wastes of Central Australia, but a thorough knowledge of 

 its natural history and geology would be of high value 

 from a scientific point of view. All the expenses of Col. 

 Warburton's journey, we should say, were generously 

 borne by the Hon. T. Eden and Mr. W. W. Hughes, 

 public-spirited Australian colonists. 



The introduction occupies about one-half of this 

 volume, and consists of a carefully compiled and most 

 interesting r^sum^ of Australian exploration from Eyre's 

 daring journey in 1840 downwards ; it adds much to the 

 value of the work. Mr. Bates has discharged his edito- 

 rial duties satisfactorily. A good portrait of Col. War- 

 burton is prefixed, and the map gives one an excellent 

 idea of the route as well as of the nature of the country. 

 The other illustrations are rude but interesting. Alto- 

 gether the volume is a valuable contribution to the history 

 of Australian exploration. 



LETTERS TO THE EDITOR 



[ The Editor does not hold himself responsible Jor opinions expressed 

 by his correspondents. Neither can he undertake to return, 

 or to correspond with the writers of, rejected nianuscrifts. 

 No notice is taken of anonymous communications,'] 



Acoustic Phenomenon 



Perhaps the following description of a phenomenon in sound 

 which I have frequently observed may be of some interest to a 

 few of your readers : — 



If an observer is placed a short way, say about eight yards, 

 in front of a straight palisaded fence made with deals of about 

 three inches in width and about six inches from centre to centre 

 apart, so as to leave intervening spaces of three inches, and then 

 gives a smart clap with his hands, or, what is better, with two 

 flat pieces of wood, a peculiar echo is heard almost at the same 

 instant. 



The nature of the sound is neither that of a true musical note 

 nor of an inflection ; it appears to the ear to be somewhat inter- 

 mediate to those, inclining more at the beginning, when well 

 elicited, to a very high-pitched sound of the latter kind ; it slides 

 down until it becomes a distinctly audible musical sound at the 

 end, if the fence is 80 or 100 yards long ; with those dimen- 

 sions a moderately quick ear can easily recognise the pitch of the 

 final note to be near D on the fourth line of the treble clef. 



The phenomenon is caused by each board of the fence giving 

 rise to a resonance ; those aerial impulses succeed each other at 

 constantly increasing intervals of time, and with such a degree 

 of rapidity as to constitute a continuous sound of the kind which 

 is here described. The vibrations will be seen, from the follow- 

 ing diagram, to be neither isochronous like those of a musical 

 sound, nor to vary in their periods in the same simple order as 

 those of an inflection which is produced by sliding the bridge of 

 a monochord while it is vibrating. 



Let be the position of the observer, and d-d^ d„ d^ Sec. the 

 boards of the fence. 



Call the distance d == D, and dd — S. Then by the common 

 rule for right-angled triangles the distanc es of eac h b oard from 

 the observer are respectively V2^ V-^* + 5*, V-^'' + 45", 



