!92 



KNOWLEDGE 



[Makcu 3, 1882. 



th<< mU'llitpii of Mnr* wnnlil bo ror; Might. Binf^larly rnnaf^h, 1 

 cuniiilunHl thiH pninl, but I rnnnnt now n'mpnilwr where (know it 

 wim when I editcil the Monthly Notices of the Aiitronoinirnl Society), 

 befon* tJie ninall moons were diHCovoreii. — W. WlI.HON, J!. A. Your 

 rejoinderH, rc-rejoindera, Ac., remiiiil me murh of Bourn, J*uck. and 

 Prince I'sul, in " Lu Gmnde DuchoKse." " II doit Htv en train de 

 nionter," says Iloum j " il trnveracra— ct dencendra — il rctraveraern. 

 remimtoni, redencendra, rerotmverBcrn." " R<'remonteni," Biiya 

 Puck. " KcredcBcendni," snyB Prince Paul. " Et ca'tera, et cjctera," 

 eny« Puck. Don't you think we may nay so too ? Wo are not likely 

 to niifree. To take your illuBtratire caso (so jfood of you to treat me 

 ns you do " the duller boys in your school"), I should sny the sun 

 Bots, even in a scientific treatise— not, " the earth rotatinp carries ns 

 out of view of the snn." — Newton CR"si.ani>. Ur. Bull ouplit truly 

 to bo ashnnu'd of himself, " falling into the same egregious blunder 

 ■u Sir Isaac Newton," and I, too (being " in my senses, and espe- 

 cially OS a mathematician "), for allowing him to fall " into tlio old 

 jog trot nursery error." But my " own paper on the ' Menacing 

 Comet ' is almost as absurd ns Dr. Ball's discourse on the moon." 

 One step further, and I suppose I shall bo "as great an idiot" as 

 Sir Isaac Newton himself. But, my dear sir, if we are so foolish 

 as you say, do please notice how generous wo are ; wo miglit, by 

 aspersing Nowton and trying to detract from his great reputation, 

 seem to assert our own superiority, and get people to say of us, 

 with Bunthome, — 



If that will not suit then, which would very well suit me, 

 Why, what very, very sapient men those sapient men must be ! 

 Instead of this, we are content to follow in Newton's footsteps as 

 far as our feebler forces will take )is. How happy it must make you 

 to be able to say, " Until astronomers adopt my thooiy of polarity, 

 the science of astrononij-, or rather its exposition, must swarm with 

 fallacies, contradictions, crudities, and nonsense." — Rev. H. H. 

 HiGGiNS. Many thanks. We have forwarded business part of your 

 letter to publishers. Tlio "absurd mistake" is, as yon say, very 

 amusing. Wallenstein was singularly fortunate ; for astronomers 

 have not hitherto seen Jupiter in Cassiopeia. Napoleon's referring 

 to Venus, seen in the daj'time, as his star, was scarcely less absurd, 

 though in another way. — M. S. Ripley. The book was reviewed in 

 an early number of Knowlepge. — W. C. Because the stars are so 

 far away. On the other point— emphatically, No ; we will net discard 

 the motto beginning, ''There is no harm in making a mistake." It 

 was one of the finest things ever said. Of course, if yon choose to mis- 

 nnderstand it to mean that there is no harm in a mistake, left uncor- 

 rected, that is not our fault. Read it in conjunction with Faraday's 

 remark on fixity of opinion, and yon wiU find it contains a most 

 useful lesson. Of course, a mistake is in itself unfortunate ; but 

 as no man can ever reach the truth without making mistakes, 

 Liebig's saying remains true, even in its baldest scnRe. But 

 equally of course, what he means is, that we should all be ready 

 frankly to admit our mistakes. I believe, for my own part, there 

 is no more useful scientific rule. Nay, I will go so far as to say 

 that a mistake made by a well-known student of science, and 

 frankly acknowledged, does at least as much to advance science 

 as the discovery of a truth. But these short, pithy sayings, 

 " jewels, ten words long, that on the strctclied forefinger 

 of all time sparkle for ever," are not for the prosaic mind. 

 What do you suppose the old Greek philosopher would have 

 said, if, in response to his " Know thyself," some one had answered, 

 " I don't want to know^ myself ; I would rather know somebody 

 bettor worth knowing?" — Sia Fb. B. Letter forwarded to 

 publishers ; there may bo a day or two of delay. Letters addressed 

 to editor are not opened at the office, and, in some cases, are kept 

 a week before being opened at all. — H. A. Bulley. Fogs like the 

 dense London fogs are never seen where there is little smoke, so 

 that there must be some connection between smoke and fogs of 

 this sort. We did not notice the paragraph in the Lancet, but as 

 you report it, it seems decidedly opposed to all the evidence. — 

 W. H. H. SoAMEs. I think, if you consider the matter care- 

 fully, you will see that whatever unfairness there may seem 

 in my reply arose from your own departure from a rule 

 which has been laid down, after very careful consideration, for 

 the guidance of contributors and correspondents. You must know 

 well that a very largo proportion of the men of science of our time 

 regard the account to which you refer us only a well-meant but 

 utterly erroneous attempt to explain some of the mysteries of the 

 universe. An astnmomer like Sir George Airy says the geology 

 may do pretty well, but " the astronomy is quite wrong" ; a great 

 geologist thinks the astronomy may be right, but the writer cer- 

 tainly knew little about the earth's' crust ; and so in every single 

 branch of science which can be named. Again, it is certain that 

 while they think that way, many estimable persons, and some of 

 them scientific, too, think differently. The former may be qnite 

 wrong, and these latter right. Or you may be right in the 

 extreme view you take, that not oul'y i* tlie ax-eonnt oorrett, 



but that it WBK intended to enlighten men as to siienliSc 

 nuilters, and thai we ought, therefore, to take the apparentlj 

 plain Htntemcnti in the wcount as port of our working material. 

 But whoevi-r may Ije right or wrong, or whethsr all arc rigbt 

 in some degre*', and all in some degree wrong, has really nothing tt 

 do with na. We simply decline to have inconsipt^-nciea asserted 

 here, or attempts at harmoniaing made here. We want tu get at 

 scientific truth, by scientific reaearch, obatTvation, and cip<'rimeDt| 

 and in no other way. If you are right, and the account which jroB 

 deem plain (but many do not) is correct, it is absolutely ccrtiili 

 that the viewa to which we shall be \ed by the, perhaps mor* 

 roundabout, perhapa more direct, route of scientific inquiry, wiD 

 agree with that account in the long-run. If the way really if 

 longer, the exercise will do na all good. — A Remo.nstuant. When 

 you wTote aaying we had nothing but astronomy, you must have 

 been trjing some of the things which writers on Brain TroublM 

 describe as causing mental hallucinations. We have befon 

 us the contents of Part IV., and we find, besides correspondenoi, 

 notes, mathematics, whist, and chess, no less than thirty-two nali> 

 astronomical subjects. What can yon mean ? — J. Uakkinhoit. 

 You tell mc (I fancy I have heard it before) as bearing on the 

 inferiority question, that " a woman may not be able to sharpen a 

 pencil or throw a stone at a hen, but she can pack more articlei 

 into a tmnk than a man can." Do yon refer, in a roundabout way, 

 to tight-lacing ?—MoBEiT. More fit for others than for us. VTbtt 

 is new is not strictly true. You incorrectly define-clouds as a col- 

 lection of watery particles in the state of vaj)Our, then correctly 

 defining vapour.— P. A. Fotbeegiil. iThanks for very pleasant 

 letter. The Petersburg problem is one of the most perplexing 

 problems known. I believe I took the logically correct view in the 

 old discussion ; but if I were asked what I would pay for the 

 chance, yon may depend I would not offer what may be provt<d to 

 be the just price, viz., infinity. It would be a very interestiiig 

 subject for discussion. — Aldebaban. Putting x as the distance of 

 the earth from sun after time t, we have 

 rf'r Q 



— = — — where G=8nn'8 gravity at unit of distance. Hence, mnl- 



tiplving by 2 — and, integrating, we have ( — ) =C+ ^— 

 d( \dt / T 



therefore, 



Integrating this you will find 



(=»/ {^Dx — x^— — vers — +Ct 



And since when t = 0, i = 2>, C ' = 



2 



we have then, when a- =0 (that is, neglecting the slight difference 

 of time between the earth's reaching the centre and the surface 

 of the sun) 



/ D Dr 

 V 2G 2 



If you put in this the correct values for D, G, and v, yon will 

 get a result very near Young's. Y'on have D = 02,885,000 milee, 

 (; =324,000 :;. (Earth's radius)' (roughly), where <? = terrestrial 

 gravity at Earth's surface ; and we must reduce all the distances to 

 feet, put 3 = 322, and then t will be given in seconds. — Haliyakd. I 

 received your long paper, and preserved it, proposing to return 

 when stamps should be sent. Because, it really was too long " f 

 any use," even if my " plan were that of the E. M.. so that I mi^tj 

 be glad of " a humble paradoxer or two to pad." Y'ou certainly 

 (lid not in any way offend by discussion in 1877. By yOB 

 own account I was the offender. If, indeed, I snubbed 

 " in a way no nndcrgrad would stand from a don," 1 

 assure you it was quite unintentional. Perhaps in those days 

 did not so well know the proper course to pursue. What I meant! 

 for good-humoured fun was mistaken for sarcasm, which is, in] 

 truth, quite out of my line. 1 agree with what Dickens says i 

 of his letters (1 think), that it will not do to adopt a tone wh 

 might even be mistaken to signify. See how clever I am, and wh 

 fun everyone else. Thanks for note about the zodiacal light! 

 1 have never seen it well in England. 1 saw it very well ill 

 Bloomington, Indiana, in the spring of 18S0. The atmospherfl 

 could not under any circumstances act as a telescope to enable yo» 

 to see Venns as a crescent. More probably some atmospberi< 

 [lecnliaxity distorted Venus into apparent crescent form. — H. B 

 SuAW. Many tbaoks. Your suggestions seem excellent. — B 

 W11.XKUI.H. Sorry any papur rc^Duuned umicknowledged. W< 



