26 



NATURE 



\_Nov. 8, 1877 



how money grows, and writes for younger minds than 

 does the Rev. G. Henslow, who contributes lessons on 

 flowers, where too many technical terms are, we think, 

 introduced, especially in the first chapter. Miss Fenwick 

 Miller's lessons on the human body, and on ventilation, 

 are excellent, and so are Mr. Philip Sevan's on food, and 

 Dr. Mann's on the weather. Altogether, we congratulate 

 the publisher on the subjects selected, and the authors he 

 has chosen : no doubt the remainder of the lessons that 

 are to be issued will confirm the high opinion we have 

 formed of those already before us. W. F. B, 



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 communications. 



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.'\ 



Appunn and Koenig. — Beats in Confined Air 

 In my letter published in Nature (vol. xvi. p. 227), I stated 

 that I should re-examine the question of the discrepancy between 

 Appumi and Koenig, and inform you of the result. During the 

 whole month of September I was engaged in very carefully 

 counting and recounting Appunn's tonometer in the South Ken- 

 sington Museum, the reeds of which had got a little out of order, 

 a circumstance which did not interfere with the ascertainment of 

 pitch, but disposed at once of any errors in Appunn's pendulum. 

 I employed one of Webster's ship chronometers, which was rated 

 to lose one second daily, and counted each set of beats repeatedly 

 through one or two minutes. I ascertained by this means that 

 the objections made by Koenig on the score of false pendulums 

 and false counting were entirely groundless, and that the former 

 determinations of the relative pitch of Koenig's forks and 

 Appunn's reeds, made by Dr. Preyer and myself, were prac- 

 tically correct. 



But as Lord Rayleigh pointed out in Nature (vol. xvii, p. 12) 

 the practical agreement of the results obtained by Professors 

 Mayer and MacLeod, and by his own new method there de- 

 scribed, with Koenig's, serves to show that there is a physical 

 phenomenon to be accounted for. Mr. Bosanquet had drawn 

 my attention to the subject several months ago, and my own 

 experiments on the beating of disturbed consonances had led 

 me to the same conclusion. Accordingly I had devised a series 

 of experiments for ascertaining the fact, the nature of which I 

 lately communicated to Lord Rayleigh ; but as they required 

 the use of two tonometers excited by separate bellows, there 

 were difficulties in the way of making them, which I did not 

 overcome till this week. To-day I made the first of these 

 experiments, lasting four hours or more, and ascertained — 



1. That the beats of the harmonium reeds in Appunn's tono- 

 meter are affected by taking place in a confined space of air. 



2. That they are accelerated, and 



3. That the acceleration, being roughly about one per cent., 

 will probably, when completely ascertained, account for the 

 discrepancy observed. 



Details have been sent privately to Lord Rayleigh ; they are 

 too incomplete for publication. The experiments will require 

 many weeks to complete with the necessary accuracy. But in 

 the meantime I hasten to communicate an important acoustical 

 fact which may bear upon many other phenomena besides the 

 ascertainment of absolute pitch. Alexander J. Ellis 



25, Argyll Road, Kensington, November 3 



The Radiometer and its Lessons 

 As I now learn for the first time what are the grounds on 

 which Prof G. C. Foster based his inculpation of me, I may ask 

 for a very few last words. I fully admit that in giving a sketch 

 of the history of the Radiometer, I intended to attribute to Mr. 

 Crookes that he had in the first instance put a wrong interpre- 

 tation upon his own results ; because I believed that this was a 

 simple fact, well knovm to everybody who had followed the 

 history of the inquiry. And Prof. Carey Foster has not called 

 in question the correctness of my statement of the general im- 

 pression which prevailed among scientific men, alike when Mr. 

 Crookes first exhibited his radiometer at the soiree of the Royal 



Society, and when its phenomena were discussed at the subse- 

 quent meeting. Having fol'owed that discussion with the 

 greatest interest, I cannot now recall one word that was not in 

 harmony with the "direct impact" doctrine, or that suggested the 

 idea of " heat reaction " through residual gas. If the question 

 had been then asked, whether the rotation would continue to 

 take place in an open vacuum (were such possible), or in a per- 

 fect vacuum, — so as to eliminate all " reaction," through residual 

 gas, between the vanes and the containing flask, — I believe that 

 the general, if not the unanimous, verdict would have been in 

 the affirmative. Certainly I heard nothing from Mr. Crookes on 

 the other side, he having previously spoken of the dependence 

 of the "Repulsion resulting from Radiation on the presence of 

 residual gas as 'impossible to conceive.' " 



It is clear, then, that in referring to this then prevalent view, 

 I no more wished to put Mr. Crookes in the wrong, than I wished 

 to put in the wrong my very excellent friends among the other 

 eminent Physicists who shared it ; the special purpose of this 

 part of my paper being to bring out, as strongly as I could, the 

 thoroughly scientific and philosophical method in which Mr. 

 Crookes aftenuards worked himself right. If this is not expressed 

 in as much detail as Prof. G. C. Foster would have approved, 

 it surely afforded no adequate ground for his going out of his 

 way to charge me with having "depreciated Mr. Crookes's 

 merits." Yet this is the only ground that I can find in the whole 

 of Piof. Carey Foster's statement, for what I could not but regard 

 as a very grave imputation. 



On Mr. Crookes's reply I shall make but a single remark, witli 

 reference to his perfectly correct citation of the latter part of my 

 conversation with him, on the occasion of his receiving the 

 Royal Medal. If I had not found, afier the publication of my 

 Lectures (in which I said nothing but what wfs respectful to Mr. 

 Crookes), that he had himself been "digging up the hatchet" 

 which 1 was quite disposed to keep buried, by giving his public 

 attestation to the "spiritualistic" genuineness of what had been 

 proved to be a most barefaced imposture, I s-hould not have again 

 brought his name into the controversy. But I felt that his yrtatly 

 increased reputation as a Scientific man would do an increasing 

 injury to what I honestly believed to be the cause ot reason and 

 common sense, not only in this country but still more in the 

 United States. 



Since the death of Prof. Hare, not a single scientific man cf 

 note (so far as I am aware) has there joined the Spiritualistic 

 ranks; but the names of the "eminent British scientists," Messrs. 

 Crookes and Wallace, are a " tower of strength " to the various 

 orders of "mediums" — rapping mediums, writing mediums, 

 drawing mediums, materialising mediums, test mediums, photc- 

 graphic mediums, trance mediums, healing mediums, and the 

 like — zvhose names form many columns of the " Boston Trades' 

 Directory." And the now notorious impostor, Eva Fa}', has been 

 able to appeal to the " endorsement " given to her by the " scien- 

 tific tests" applied to her by "Prof. Crookes and other Fellows 

 of the Royal Society," which had been published (I now find) by 

 Mr. Crookes himsell in the Spiritualist in March, 1875. Within 

 two months of that date, as Mr. Maskelyne has publicly stated, 

 an offer was made him (I have myself seen copies of the letters) 

 by Eva Fay's manager, that for an adequate sum of money the 

 *' medium " should expose the whole affair, scientific tests and all, 

 '\complicating at least six big guns, the F.R.S. people,''^ as she was 

 not properly supported by the Spiritualists, 



I have therefore felt it incumbent on me to show that in dealing 

 with this subject Messrs. Crookes and Wallace have followed 

 methods which are thoroughly ««-scientific ; and have been led by 

 their " prepossession " to accept with implicit faith a number of 

 statements which ought to be rejected as completely un- 

 trustworthy. 



My call to take such a part — which I would most gladly lay 

 aside for the scientific investigations which afford me the purest 

 and most undisturbed enjoyment — seems to me the same as is 

 made upon every member of the Profession to which I have the 

 honour to belong, that he should do his utmost to cure or to 

 mitigate bodily disease. The training I originally received, and the 

 theoretical and experimental studies of forty years, have given me 

 what I honestly believe (whether rightly or wrongly) to be a rather 

 unusual power of dealing with this subject. Since the appea-ance 

 of my Lectures I have received a large number of public assurances 

 that they are doing good service in preventing the spread of a 

 noxious mental epidemic in this country ; and I have been 

 privately informed of several instances, in which persons who 

 had been " bitten " by this malady, have owed their recovery to 

 my treatment. Looking to the danger which threatens us from 



