532 



♦ KNOWLEDGE ♦ 



[Dec. 26, 1884. 



believe this on liis authority, for it is a thing which he cannot 

 know without ceasing to be man." "No eminence of character and 

 genius can give a man authority enough to justify us in beHeving 

 him when he malses statements implying exact or universal know- 

 ledge." 



Further on, in the quotation from Ilaeckel, we have : " Every 

 atom has an inherent sum of force, and is, in this sense, gifted with 

 a soul." Though we may not question the first part of this state- 

 ment, is there any reason for our concluding that this " sum of 

 force'* is a sort of ** soul," and can be expressed in terras of con- 

 sciousness and will ? Very probably, as Haeckel says, without a 

 notion of attraction and repulsion, tlie phenomena of chemistry are 

 inexplicable ; but what warrant is there for making " pleasure" 

 and "desire" concomitants of attraction, and "displeasure" and 

 "loathing" concomitants of repulsion:' Is it for a moment coil' 

 reirable that atoms are, or can he, conscious of their oicn movement ? 

 To assert that two atoms of hydrogen and one of oxygen, or one of 

 carbon and two of oxygen, c?e^■^Vc to come into contact with each 

 other appears to me to be not much different from a rc-establish- 

 ment of the polytheistic ideas of our rude forefathers. 



J. T. Rol'TLEDGE. 



WHAT SHOULD THE EARTH CONSIST OF THEORETI- 

 CALLY, IF LAPLACE'S "NEBULAR THEORY" IS 

 CORRECT ? 



[1541] — A strong argument advanced in favour of the nebular 

 theory of Kant, Laplace, and Herschel, is that the specific gravity 

 of the planets varies inversely with their distance from the sun. 

 The argument being that each planet possesses an average specific 

 gravity which is equivalent to that possessed by the outer layer of 

 the sun at the moment of that planet's separation from it. This 

 theory appears to be approximately true, but it has yet to be 

 shown why the earth, whose specific gravity is about 3, should be 

 composed of many elements whose specific gravities differ widely 

 from this figure. Surely the layer of the sun from which 

 a planet was formed, being in a molten state, would contain 

 elements whoso specific gravities were the same as the average 

 specific gravity of that layer, and, if these elements were in a 

 liquid condition, still this would not explain the great differences in 

 the specific gravities of terrestrial elements. The only way to 

 account for the presence of elements in the earth — like platinum 

 sp. gr. 22, or potassium, or lithium, at the other extreme — appears to 

 be to assume that the heat caused by the rupture of each planetary 

 ring would raise the temperature of the resulting planet to such a 

 point as would cause the dissociation of the contained elements, 

 which, on subsequent cooling, would form elements of higher 

 specific gravity by condensation. Giles Daubeney. 



[Wb.atever weight may attach to Mr. Daubeney's inferences, his 

 numerical data are, to say the least, vague. To begin with, the 

 specific gravity of the earth, instead of being 30, is really 5'07. It 

 is true that that of Meri'ury is 70; but, while Saturn's is only O'CS, 

 the specific gravity of Uranus is 0-99, and that of Neptune 0-9G ; 

 which accords but indifferently with the notion of variation 

 "inversely with their distance" from the sun. — Ed.] 



CURIOUS SUNSET. 



[1515] — This evening, about 4 p.m., walking along the East 

 Cliffs towards the town, I witnessed a remarkakle and somewhat 

 unusual, sunset. The western sky, above the sun (which was 

 hidden, as also a great part of the western horizon by the ridges of 

 Kinkell Braes), seemed to be covered by a light-grey vapour — 

 almost white, which shaded into the clear sky above without per- 

 ceptible edge or break, as in ordinary clouds. Through rifts in this 

 vapour, were clearly discerned bands of prismatic colours, as 

 distinct as in the rainbow, but perhaps softer in tint, also the bands 

 were broader. From the shape of the visible bands of colour it 

 seemed as if they radiated from the setting sun in the same way as 

 the fan. shaped pencils of light often seen on grey clouds in the 

 west. They were all about the same height — rather less, I should 

 think, than 45° above the horizon. The loose clouds floating in the 

 clear sky above were deep purple-black, with a coppery tinge. I 

 do not know if anything of the same kind has been observed in 

 other places, or what the cause of this phenomenon could be. 



25, South-street, St. Andrews, N.B. A. Werner. 



POWER OF PERCEPTION. 

 [1546] — To how many objects can we attend at once ? Locke, 

 Brown, Stewart, Reid say only one ; but this assertion has been com- 

 pletely reduced to absurdity by Leibnitz, Hamilton, and others. 

 Charles Bonnet and Bestutt-Tracey both say that six objects are 



the maximum, and Hamilton agrees with them. Tucker says four. 

 I have just been testing the matter myself, though without arriving 

 at any very distinct conclusions. I found, to begin with, that I 

 could easily "concentrate my consciousness" on two objects — a 

 matchbox and an inkpot. I added a knife, then a book, then a- 

 watch, and sixthly a bottle. I found that I conld be still conscious 

 of each and all of these objects without any noticeable mental con- 

 fusion. I added three new objects simultaneously, and at liret di<l 

 not feel that the result was affected. But as I endeavoured to 

 realise that, individually and collectively, nine objects wen- 

 lying before me, I seemed to experience a mental check, 

 I felt that, were those nine objects animated beings, I could not 

 grasp all and the phenomena of all simultaneonsly. After trying 

 other variations, I have come somewhat dubiously to the conclusion 

 that six is the nnmber nearest to correctness. If six is not right, 

 seven is more right than five. What do readers of Knowledo 

 think about it, may I ask ? Fked. W. Clewoeth. 



[This is largely a matter of education. The incipient observer 

 with the Transit Instrument is at first terribly puzzled at having to 

 count the seconds ticked by the pendulum of his clock, to watch 

 the star as it crosses the spider lines in succession ; to estimate the 

 second and tenth of a second at which it is actually on each " wire," 

 and to write down his results all simultaneously ; although, after 

 sufficient practice, he does all this automatically. See, too, the 

 account of the way in which the famous French conjurer, Robert 

 Houdin, prepared for some of his tricks, as related by Dr. Carpenter 

 on pp. 205 and 206 of his " Mental Phyeiology" (Fourth Edition).— 

 Ed.] 



LETTERS RECEIVED AND SHORT ANSWERS. 



F.R C.P. To append prices, as you suggest, would be to con- 

 vert descriptive articles into advertisements pure and simple ; 

 which is wholly foreign to our purpose. — Ax Anoxyuois Coebe- 

 SPONDE.NT (whose letter bears the Chesterfield postmark) sends a 

 leaf of the English Mechanic for Dec. 19, 1873. Why, I have not 

 the smallest conception.- — J. B. Libby. See Knowledge for Nov. 

 21, p. 431, column 2. My own impression lis, though, that your 

 object-glass is faulty. — J. W. Alexaxder. Do yon seriously suppose 

 that the aether is no? matter!' 1 — Architect. No donbt, the people 

 you name would understand the misapplied marks; but I am 

 wholly in accord with the reviewer that this does not render their 

 use less (scientifically) indefensible. — F. W. H. You wander too 

 near the confines of forbidden ground to allow of the insertion of 

 your letter. — SEPirAGEXAKifs. Your kindly letter is most gratify- 

 ing. The only paper at all answering the description of that to 

 which your query relates is The Inquirer, a, Unitarian organ. — 

 P. J. L. Yon apparently admit Swedenborg'a assumptions. 

 I regard him simply as a monomaniac, suffering under hallu- 

 cinations; who was as much — or as little — inspired aa "General " 

 Booth. Hence I can recognise no validity whatever in your 

 arguments. — J. T. RotrrLEDGE. To append the prices of books 

 would be to make reviews merely publishers' advertisements. The 

 work to which your question relates costs half-a-crown. In writine 

 matter which is to be printed, please do so upon one side of tliu 

 paper only. — W. S. C. Religion is a matter of fact ; theology one 

 of opinion. It would be utterly foreign to our purpose to pretend 

 for an instant here (o prescribe the limits of belief to yourself ur 

 anyone else. All that need be said is that scientific investigation 

 must be conducted strictly by the scientific methods of observation 

 and experiment, and that no craven fear of the consequences mtist 

 be suffered to daunt the earnest and sincere seeker after Truth. — 

 George Lacv. I must refuse to be entrapped into a purely theo- 

 logical discussion. Would all the conventionalisms you yourself 

 employ bear an absolutely rigid interpretation ? You would pro- 

 bably speak of the Sun as he, the Moon as she, of " His Grace " 

 the Duke of Puddledock, and so on, without any serious intention 

 of imputing sex and personality to cither of those luminaries, or 

 graciousness to a man who may have figured in the Divorce Court . 

 — William Johnston. Pray buy a shilling elementary book on 

 mechanics. Its perusal may save you from such exhibitions as yoti 

 make on your ninth page, and show yon how utterly impossible it 

 is that comets of long period can revolve round two separate suns ! 

 Apropos of your fourteenth page, would yon be surpriced to hear 

 that the density of Mercury is 1'21 times that of the earth : that 

 of Saturn only 012 of ours ? — H. M. I'. I imagine (bnt am not 

 certain) that the preface is actually in type. I could not commu- 

 nicate the substance of vour letter to its writer in time to insure 

 any alteration — always supposing that he considered it necessniy- 

 — St. J. H. Many thanks for all the trouble you have kindly 

 taken, but the subject has already been thrashed out in these 

 columns. — A. B. (Glasgow). I am very sorry to be compelled to 

 decline to furnish the name of the manufacturer. You surely do not 

 wish me to advertise what I denounced as a species of fraud. — 



