May i8, 1876] 



NA TURE 



47 



of profound biological importance with large practical 

 bearings. It would be a disgrace to science, or rather to 

 scientific men, were the present uncomfortable dead-lock 

 of conflicting evidence to be permitted to remain for any 

 length of time. Prof Tyndall will, of course, publish 

 descriptions of his experiments in the fullest possible 

 detail ; but the interested public have no just balance in 

 which to weigh the accuracy and skill of Prof Tyndall 

 against that of Dr. Bastian. The high position of our 

 great teachers undoubtedly carries with it certain obliga- 

 tions ; and we scarcely think that we ask too much in the 

 interest of science when we venture to suggest that steps 

 should be taken towards the little friendly arrangement 

 necessary for the settlement of the question. 



Douglas A. Spalding 



OUR BOOK SHELF 



Solid Geometry. By Percival Frost, M.A. Vol. i. 

 pp. 422. (London : Macmillan and Co., 1875.) 



This excellent treatise is a revised and considerably 

 enlarged second edition of the similar treatise brought 

 out some few years since under the joint editorship 

 of Messrs. Frost and Wolstenholme. The engrossing 

 duties consequent upon Mr. Wolstenholme's holding the 

 post of Professor of Mathematics at Cooper's Hill, have 

 prevented his taking part in the bringing out of the present 

 work. Great additions have been, and are being, made 

 in this subject, as may be inferred from the fact that this 

 first volume consists of 422 octavo pages, and even in this 

 space many modes of treatment are omitted. "We can- 

 not, however," writes Mr. Frost, " in a volume of mode- 

 rate compass, pretend to include all the dual results to 

 which our equations might give rise, but must confine 

 ourselves to a development of the methods most generally 

 useful." 



The author reserves for his second volume " those parts 

 which are chiefly interesting as pure geometry," bringing 

 into the volume before us as much as he could, those 

 parts of the subject which are more especially required 

 by students who take up physical subjects. Prefixed to 

 the text is a full table of contents : indeed both in this 

 work and that by Dr. Salmon on the same subject, the full 

 list reminds us (though drawn up on different principles) 

 of the diagnoses of the natural orders prefixed to text books 

 on the British flora. 



The text is written with extreme lucidity, and the diffi- 

 culties to be met with in its perusal do not arise from the 

 style, but from the inherent difficulty of the matters 

 treated of. In two or three places we come across the 

 phrases " easy to see," p. 154, '' not hard to show," p. 157, 

 and the like ; of course here they are not intended to cover 

 inability to expound the matter within reasonable com- 

 pass, but still we think the proof might have been sketched 

 out. When the student is going through the text step by 

 step, he may even be able to work out the process by 

 himself, but it is not so easy when the book is taken up 

 at other times, when the previous steps in the reasoning 

 are not fresh in the mind. 



We note in Art. 192 that the elliptic sections are not 

 pointed out ; this and the definition of the radical plane 

 \\ 166) which reads somewhat curiously to our mind, are 

 the only defects we have been able to detect — we had 

 marked many passages for comment, but all is so carefully 

 done, and the work brought down to the latest discoveries, 

 that we shall content ourselves with saying that the book 

 is well entitled to a place by the side of Dr. Salmon's 

 treatise. Mr. Frost, it is well known, emplo}s the term 

 " conicoid " for the surface of the second degree, and in 

 the present work he gives his reasons for persisting (as 

 he expresses himself) in retaining the term. We must 



just cite here the concluding part of his remarks ; the 

 surface of the second degree, " well deserves a distinctive 

 name instead of being recognised only by its number, a 

 mode of designation which, I am informed, a convict feels 

 very acutely. Man might be always called a biped, be- 

 cause besides himself there exist a quadruped, an octopus, 

 and a centipede, but, on account of his superiority, it is 

 more complimentary to call him by some special name." 



The list of typographical errors is, we believe, very 

 small, and all are easily corrigible by the reader. The 

 appearance of the book leaves nothing to be desired. 



Physiolo^ische Methodik : ein Handbuch der Practischen 

 Physiologie. Von Dr. Richard Gscheidlen, Professor 

 an der Universitat zu Breslau. Erste lieferung. 



Dr. Gscheidlen has undertaken to supply physiological 

 students with a book which undoubtedly they very much 

 need. He proposes to give a detailed and full account of 

 the instruments and methods of practical physiology, and 

 to consider the experimental basis on which our know- 

 ledge of the functions of the animal body are founded. 



The book is to be published in parts ; the first part, 

 which we have before us, treats at considerable length of 

 the measurements of volume, temperature, time, &c., 

 needed in physiology and of the various instruments used 

 in such measurements. It contains also the beginning of 

 a chapter on physiological instruments and methods in 

 general. 



Altogether the present part gives good reason to hope 

 that the work, when completed, will not only succeed in 

 its main object of being useful to beginners, but will also 

 be a valuable book of reference in physiological ways and 

 means. We shall, however, reserve detailed criticisms 

 till the book is published as a whole. J. N. L. 



LETTERS TO THE EDITOR 



[ 27te Editor dots not hold himself responsible for opinions expressed 

 by his correspondents. Neither can he undertake to return, 

 or to correspond with the -uiriters of, rejected manuscripts. 

 No notice is taken of anonymous communications. \ 



Periodicity of the Fresh-water Lakes of Australia 



The fresh-water lakes of Australia, though insignificant in 

 size in comparison with the extent of the country, possess several 

 features of considerable interest to the naturalist. Lake George, 

 which is generally considered the largest sheet of fresh water on the 

 Continent, is only some twenty-three or twenty-four miles in 

 length and seven miles in breadth at the widest part, and even 

 this lake had no existence twenty-four years ago. A bit of 

 swampy ground across which drays could pass, occupied, in 

 1852, what is now the lowest part of the lake-bottom, and the 

 rest was taken up by squatters and small farmers, who litde 

 dreamed, when they settled on the rich alluvial plain, that within 

 a few years they would be hopelessly driven from their homes by 

 the advancing waters. The present lake is situated, at an eleva- 

 tion of about 2,000 feet above the sea, at the lower end of a 

 shallow basin formed by a fork near the southern extremity of 

 the Blue Mountains, and about 150 miles from Sydney. This basin 

 is some forty to fifty miles in length, and from fifteen to twenty 

 miles in breadth, the mountains rising somewhat rapidly to a 

 height of several hundreds of feet on every side except the south. 

 The depth of the water at the present time is only from 25 to 

 30 feet, which, considering the extent of land submerged, 

 affords a strong argument in favour of the supposidon that the 

 lake existed in past times, and was at least as extensive as it is 

 now. An examination of the banks of the creek which runs 

 into the head of the lake confirmed this hypothesis, and led me to 

 believe that it has at one time been much more extensive than it is 

 at present, for the horizontal layers of alluvial deposit could be 

 traced along either bank at an elevation of 10 or 12 feet above 

 the present lake-surface. This, however, could not have been 

 the case within the last one hundred years — probably not within 

 many hundreds of years — for the present lake is fringed with 

 broad expanses of partially submerged forest trees, that must 

 have attained a growth of more than a century before the waters 



