i8o 



NATURE /' 



1 



\Jan. 3, 1878 



auditory. To such teachers as have never studied or 

 thought on scientific questions themselves, our advice 

 would be to content themselves with placing Prof. 

 Huxley's book in their school-libraries, and not to run 

 the risk of spoiling its teachings by filtering them through 

 their own minds. 



We have spoken at such length on the value of this 

 work to the teacher, as to leave but little space for refer- 

 ence to its interest to the general reader, yet this is by no 

 means small ; to those who seek an " introduction to the 

 study of nature," which shall be at the same time both 

 sound and readable, exact and untechnical, we most 

 heartily commend the work before us. 



We are informed in the preface that the idea of 

 this work has long been entertained, and its plan 

 and methods frequently revolved in the mind of the 

 author. It is probable that not a little of its present 

 excellence is due to this slow maturation of its plan, 

 assisted, as we learn that its development has been, by 

 its embodiment in two successive courses of lectures — on 

 the shorthand notes of one of which the present book is 

 based. In seeking for an editor to relieve him of the 

 more trying labour of book-making. Prof. Huxley has been 

 fortunate in securing the services of Mr. Rudler, whose 

 knowledge of a great number of branches of science 

 is combined with much literary skill. To this cause 

 we may attribute the small number of inaccuracies in 

 either fact or expression which a careful perusal of the 

 work has revealed. Such as do occur may be easily 

 remedied in the new edition, which we have no doubt will 

 soon be called for. 



In concludmg this notice we cannot refrain from con- 

 gratulating its author upon the production of the work, 

 and at the same time of assuring him that among all the 

 labours he has undergone, and the sacrifices he has made 

 on behalf of elementary education in this country, none is 

 likely to produce more valuable and more enduring fruit 

 than this much-needed model of the art of teaching the 

 fundamental truths of natural science, the appearance of 

 which at the present time we cannot but regard as being 

 most opportune. J. W. J. 



OUR BOOK SHELF 



Myths and Marvels of Asironomy. By Richard A. 



Proctor. (London : Chatto and Windus, 1878.) 

 The author observes in his preface that " the chief charm 

 of astronomy with many does not reside in the wonders 

 revealed to us by the science, but in the lore and legends 

 connected with its history, the strange fancies with which 

 in old times it has been associated, the half-forgotten 

 myths to which it has given birth," and further remarking 

 that in our own times myths and fancies, startling inven- 

 tions and paradoxes have also found place, he has framed 

 the present volume to meet the tastes of the class of 

 readers which he believes to be specially interested in 

 such matters. 



In a work confessedly written with this object in view, 

 perhaps it (will hardly be expected that there can be 

 much to require notice in a scientific journal. An im- 

 portant point will be accuracy of detail, and in this 

 respect, except in two or three cases, we remark little to 

 which exception can be taken. Amongst other subjects, 

 the author enters upon " the religion " and the mysteries 

 of the Great Pyramid, "Suns in flames," the rings of 

 Saturn, comets as portents, the notorious lunar-hoax of 

 1835-36, and the origin of the constellation-figures. He 



is unlucky in his notice of the first discovery of the 

 famous star of Tycho Brahe in 1572,'reproducing from 

 Sir John Herschel's " Outlines," the story of Tycho's 

 attention having been first directed to the object on the 

 evening of November 11, by seeing "a group of country 

 people gazing at a star which he was sure did not exist 

 an hour before." This story is as much a mylh as any- 

 thing in the volume before us, as will be evident to the 

 reader who consults the account of his first observation 

 and of the observations of others given by Tycho himself, 

 and it is strange that the statement which has misled 

 Mr. Proctor should have been continued in the various 

 editions of Sir John Herschel's "Astronomy" since 

 the year 1833. The account given in the chapter "On 

 some Astronomical Myths" of the actual position 

 of the intra-Mercurial planet question is too incomplete 

 to enable the reader to form a competent judgment there- 

 upon, though it may leave him under the impression that 

 there is something mythical about it. Mr. Proctor appears 

 to reject " the idea of wilful deception " on the part of 

 astronomical observers — in which case the mere expres- 

 sion of disbelief in the existence of an intra Mercurial 

 body or bodies does not assist explanation of recorded 

 observations, more particularly where motion has been 

 remarked. There are a few numerical errors in the 

 volume, as in the note on p. 235, where it is stated that 

 the comet of the August meteors has " a period of at least 

 150 years ;" so long a period would be irreconcilable with 

 the observations, and the very complete investigation by 

 Prof. Oppolzer assigns 121^ years as the most probable 

 length of the revolution. But as already stated there is 

 general accuracy of detail, and the volume will doubtless 

 be found acceptable to the particular class of readers for 

 whom it has been prepared. 



LETTERS TO THE EDITOR 



[The Editor does not hold himself responsible for opinions expressed 

 by his correspondents. Neither can he undertake to return, 

 or to correspond with the writers of, rejected manuscripts. 

 No notice is taken of anonymous com-munications. 



The Editor urgently requests correspondents to keep their letters as 

 short as possible. The pressure on his space is so great that it 

 is impossible otherwise to ensure the appearance even of com' 

 munications containing interesting and novel facts, "^ 



Electrical Experiment 



The inclosed letter gives an account of an experiment in which 

 an electric current appears to be produced by the direct action 

 of gravity, a result which, if clearly established, would be new 

 and of considerable scientific interest. 



In trying to repeat the experiment yesterday I observed a con- 

 siderable deflexion of the galvanometer in the direction described 

 by Mr. Pirani, but as this deflexion seemed to occur some 

 seconds after the inversion of the tube, I examined the tube and 

 found a small bubble of air working its way up through the 

 solution, and as soon as it came to the top of the tube the 

 deflexion occurred. 



I have not yet had time to repeat" tha experiment without the 

 bubble, but I mention this to show that care must be taken to 

 secure that the electrolyte is homogeneous, and that it does not 

 contain anything which will either sink to the bottom of the tube 

 or float to the top, so as to act alternately on the two electrodes. 



The fact that the deflexion continued for some time after the 

 lube was placed horizontally seems to indicate the possibility of 

 something which was shifted from end to end when the tube was 

 inverted, but remained where it was when the tube was only laid 

 on its side. J. Clerk Maxwell 



Cavendish Laboratory, Cambridge, December 28, 1877 



" University of Melbourne, Oct. 30, 1877 

 " My Dear Sir, — On page 317 of vol. i. of your 'Electricity 

 and Magnetism ' it is pointed out that a greater electromotive 

 force is required to produce a given current between zinc elec- 

 trodes in a solution of sulphate of zinc when zinc is carried up- 

 wards than when it is carried downwards . 



"I am not aware that it has been noticed that by the same 



