Maucu 13, 1SS5.] 



♦ KNOWLEDGE ♦ 



225 



opinion, philosophers shnuUl bo considered to hnve ii consensus of 

 opinion upon." But what is this but, in fact, meeting an argument 

 aa fallacious because it is peculiar to the man who advances it by an 

 argument as admissible because it is advanced by myself. 



I may, however, be wrong in my own assertion that there is no 

 consensus of philosophic opinion. And this is where I desire to bo 

 sot right if I am wrong. There certainly ought to be a consensus 

 of opinion somewhere. If there is, where is it ? What ground 

 does it cover? On what ]irinciples, and how far, does it go? 



But if I am right, that there is no consensus of opinion, can this 

 striking fact bo made the subject of philosophic consideration ? 



Generally, what hinders discussion is irritation ; and irritation 

 and anger start up from a great many sides and from a great 

 many reasons. Directly people's own pet theories are controverted, 

 a natural resentment takes possession of them, and when this is the 

 case, in however small a degree, there is no hope, or little hope, of a 

 satisfactory conclusion being come to from any argument they may 

 embark in. 



The question, then, is how to arrive at that perfect equanimity 

 of temperament in which the mind is prepared to accept as truth 

 that which to the mind, for the time being, is shown to bo truth. 

 If a man is absolutely willing to accept truth, and at all costs to 

 act npon it, then he must be admitted to be in that serene, philo- 

 sophic state of mind in which it would be most satisfactory to 

 maintain an argument with him. 



But, I would ask, can it be shown what that state of mind must 

 be ? Can it bo demonstrated so as to be beyond all manner of 

 doubt? I think it can. But as this my opinion goes for as little 

 as, and perhaps less than, any other man's opinion, I should not like 

 to state what it is before I hear what others, who know more of 

 philosophy than I do, have to say on the subject. Hoping I have 

 not trespassed too long on your space, L. B. K. 



[By far the greater nnmber of disputants appear to do their best 

 to justify Punch'/: imperishable definition: '"Toleration is letting 

 yon believe as I believe. Intoleration is your wishing me to believe 

 as you believe." — Ed.] 



THE DOCTRINE OF CHANCES (Matthew xv. v. 11.) 



[1637] — With regard to a letter of mine which you were good 

 enough to insert in last week's Knowlkdgk, concerning a problem 

 in the calculation of chances, I regret to find that I am wrong, and 

 that the solution given in " Whitaker's Almanack " is right. 



I believe there is a saying at Cambridge that the chances are 

 that a student who tackles a problem connected with the doctrine 

 of chances will come to grief. I shall accept this caution in future, 

 and not venture again to give an opinion on said topics. 



Cius. G. SnAvr. 



[I print this letter as containing a warning alike to myself and 

 to the readers of Knowledge. It never occurred to me for an 

 instant that any one would attack a mathematical deduction in so 

 ably -edited a work as " Whitaker's Almanack " without being abso- 

 lutely sure of his ground ; and hence, pre-occupied as I am, I did 

 not attempt to check Mr. Shaw's calculations. For the future, no 

 mathematical or quasi-mathematical letter will be inserted until I 

 have myself read it carefully through.] — Ed. 



TERMITES AXD NATURAL SELECTION. 



[1638] — There are two points in Dr. Hutchinson's paper (p. 142) 

 which should scarcely pass without notice. He says he believes 

 the wings of termites are a provision of Nature for lessening the 

 species, by means of its devourers in the air. Of course he is 

 aware that our lamented "Illuminato" denies this doctrine. He 

 holds that even the -subtlest organs, such as tbe eye (" that most 

 pure spirit of sense") are due to Natural Selection, and that this 

 can never operate to the injury of the creature. Could not frost, 

 disease, old age, or some other simple means, destroy the ter- 

 mites r What does the grand law of gradation say about the 

 matter? Numerous species of ants and other insects eventuate 

 in wings ; is it in their case to cause their destruction ? 



A point even more important is that of the survivors, or rather 

 slain. We here take notice, as in so many other cases (c.i., shoals 

 of fishes) that the survivors do not survive for Natural Selection — 

 the unlucky are purely unlucky, not the weakest and worst. This 

 I have always thought to be a weak link in the Darwinian chain. 

 The whole question is by no means decided, but, on the contrary, 

 still before the court. Pendente lite, we must still suspend our 

 verdict. Commentator. 



LETTERS RECEIVED AND SHORT ANSWERS. 



CoSMOPOLiT.\N is anxious to communicate with Mr. McMeister 

 (letter 1619, p. 181) on the subject of inscribed rocks; and C. W. 

 Dtmond, F.S.A., writes, in connection with the same subject, that 



rock-inscriptions, similar to those sketched by our corrcspondouti 

 have been found in localities as 

 widely separated as Scotland and 

 Fiji ! Failing any intimation of 

 Mr. M.'s locuK in quo, Mr. Dymond 

 points out that it is im|)os8iblo to 

 say whether ho has made a dis- 

 covery or not. — A Ueuin.nek. When 

 theRight Ascensions and Declinations 

 of two stars are given, the angular 

 distance between them is obtained 

 trigonomctrieally, as shown in 

 figure. Let P be tho pole, and S 

 and S' our two stars. Then P S and 

 PS' will bo their polar distances, 

 and S P S' tho diffi'renco of their 

 Right Ascensions (wo will call this 

 P). Draw SM perpendicular to 

 P S' produced. Then R . cos P = tan 

 PMcot.PS. Houco tan.PM = co.') 

 P . tan P S. Further S'M - P M - P S', and cos 1' M : cos S'M : ; cos 

 PS : cos S S' (the angle we require). Let us illustrate this nume- 

 rically. What is the angular diatanco to-night between Aldebarau 

 R.A. Ih. 29m. 198:is. and Dec. IG^ 10' 28G" N. (i.e., Polar 

 distance 73° 43' 31-4"), and Sirius R.A. (Ih. 40m. 5-7Gs. and Dec. 

 16° 33' 57-1" S. (i.e.. Polar distance lOG' 33' 57-1") ? Hero we have 

 given P. 2h. 10m. 45 933. -32' 41' 28-95", PS 100° 33' 571"; and 

 P a' 73° 43' 31-4" to find S S'. 



SS' = 4G 1 3-85 cos 9-8416320 



So that Aldebaran and Sirius are 46' 1' 3-85" .ap.-irt on an are 

 of a great circle. I have used 7-fi^ure logs, for great accu- 

 racy, but wo could have got within 07" of the truth by 

 employing G figures only. Try Ball's "Astronomy," in Long- 

 man's Text-books of Science. — J. Webb. 1 do not fancy that 

 the "coal sacks" have ever been specially treated of in any 

 ordinary works on astronomy. See Sir John Herschel's "Cape 

 Observations." — A Const.vnt Re.\der. No ; the Patent Law makes 

 no provision for the man who keeps his invention to himself, 

 whether it be his poverty or his will that consents to its conceal- 

 ment. You can buy any Act of Parliament from the Queen's 

 printers, Messrs. Eyre & Spottiswoode. — W. G. Woolcombe. I do 

 not possess Williamson's " Dynamics." In its absence I cannot 

 presume to dictate what you shall say to your pupils. — M. D. 

 (Glasgow). Wo may take it that Jupiter's IVth satellite is 

 387,000,000 miles from tho earth when at its nearest to ns. You 

 can compute the interval in miles between London and Glasgow by 

 the formula just given above in reply to " A Beginner," and by an 

 easy calculation gather the angle which that will subtend at that 

 enormous distance! Why, what coneeivable disphieeraeut con 

 take place ? Any discrepancies between the observed and com- 

 puted times of the phenomena of Jupiter's satellite arise wholly 

 from tbe imperfection of the tables (D,amoi.<!eau's) used for the 

 computations in the Nautical Almanac. There are dynamical 

 reasons why the earth's axis can never have shifted since she 

 solidified. Perhaps you h.ave come across some reference to 

 Adhemar's vagaries. — John B. Ga.\.sby asks how to distinguish 

 the male salamander from tho female ? He has two infer- 

 tile ones in a vivarium, and, if they are both of one sex, 

 wishes to procure a mate, or ni.ales, for them. — P. W. 

 Rcdler. Received with thanks. — Eve-wit.ness. With my limited 

 capacity, I rather failed to see how things could be " totally 

 different," and yet identical. Juggle with words as you may, 

 yonr " mind," in the body, s.ay of a girl of seven, would no longer 

 be yonrsflf. This Mind and Body discussion must now cease; we 

 are drifting into the veriest logomachy. — Dr. Lewins. I am sorry 

 to exclude your really ablo letter, with much in which I agree and 

 sympathise, but really the subject has outrun all bounds. — Lima. 

 As the lectures wore extemporaneous, perhaps yon will quote tho 

 poem, or the first line of it; or give some hint as to its subject. 

 Do you mean De Quincey's rendering of Richter's " Dream of 

 Infinity," given on page 2G2 of Vol. III. of Knowledge ? — Gaccho. 



