12 



• KNOWLEDGE 



[Jan. 5, 1883. 



of tlip 17Ui, niid tlip night of the 19th reHpeetivcly ; but ns theeo 

 nrc nil stiirs of less than tlio Gth iimpnitiuk', we give uo details of 

 them in so niiTely popiihir a list of occurrenees as this. 



The moon is lio'Sdaj's old nt noon on the 5th, is new at 5 h. 50"3ni. 

 a.m., on the !)th, and enters her Kirst Quarter 4-7'Gm. after niid- 

 night on the 15th. At noon, on the !Hli, she will be 03 day old — 

 13 day old at the same hour on the 10th — and so on. At 9 p.m. 

 on the 5th, she will be in the eonstellation Scorpio; at the same 

 hour on the Gth, in Ophiuehus ; on the 7th, in Sa^ttarius ; on the 

 8th, in the same constellation, as she will be on the 9th too ; on the 

 10th, in Aquarius ; on the 11th, in Aquarius also; as she will be on 

 the 12tli ; on the 13th, in Pisces, which she will not quit on the 

 Mth or 15tli. 



Venus attains her greatest brilliancy during the early morning of 

 the 11th. She is a most conspicuous object in the south-east before 

 sunrise ; and but for her great .South declination, and consequent 

 proximity to the horizon, would be visible to the naked eye in 

 sunshine. 



0m: ^aniaiiov Contfr, 



A THEORY OF MERCURY.* 

 By Thomas Foster. 



IFEAE that many — perhaps including the editor — will con- 

 sider me entirely out of order in venturing, though not an 

 astronomer, to advance an astronomical theory. I have dis- 

 cussed (see " Leisure Readings," Knowledge Library, Vol. V.), 

 illusions in these pages, and elsewhere the probable British origin 

 of a large part of our English blood, the true plot which Dickens 

 had in view in the "Mystery of Edwin Drood," and other such 

 subjects. I have advanced a theory as to "Nature Myths in Nursery 

 Rhymes," which some critics unkindly regarded as a jest, while 

 others have, in solemn sort, denounced the theory as profane in the 

 tirst place, and incorrect — which is a trifle, however (as you would 

 say) in the second. It would be very distres.siug to me if 

 any one should for a moment imagine that the astronomical 

 theory I am about to describe is advanced in jest, or is 

 the invention of some light and trifling hour and mood. It 

 has, I beg most earnestly to assure my readers, been carefully 

 compared with many of the theories, scientific and otherwise, which 

 have been advanced during the last few years. It has not been 

 adopted until I had satisfied myself that in its chief characteristics 

 it will bear favourable comparison with some, at least, among those 

 theories. After adopting it I have, indeed, (as is only natural), most 

 sedulously nursed and fondled it, until I have become warmly 

 attached to it. It would, in point of fact, be incorrect to speak of 

 it as an adopted theory, if by that were to be implied that it is the 

 offspring of any other brain than my own. It may be — astronomers 

 I know will say it is — " a poor thing," " but," as Touchstone says, 

 ■mth a touching pathos (often misapprehended), " it is my own." 



I must confess, let me say at the outset, I am not prepared to 

 accept as just the objections with which astronomers and other 

 men of science seem disposed to regard all attempts on the part of 

 persons outside their ranks to form an opinion about the results of 

 scientific observation. If we are not to theorise about the wonders 

 of which they tell us, it can only be because they have not well 

 explained their meaning. This, indeed, is likely enough ; for most 

 of them are, unhappily, inarticulate. Like the Cyclops of old, 

 they are single-eyed (for as yet binocular telescopes are not in use), 

 but some of them speak so indistinctly when they condescend to 

 speak at all, that they would seem to have a double tongue. 

 However, it must sometimes happen that what they have 

 to say is so plain and simple in itself, that it can 

 hardly be e.vpressed indistinctly. There are limits even to the 

 use of technical expressions ; and even where technical expressions 

 are available, it will sometimes happen that by an accident a man 

 of science, through a momentary lapse of attention, will use words 

 that the unscientific can understand. Learned medical men have 

 been known to speak (when hurried, of course) in plain terms, — 

 to talk of a black eye, for example, instead of indulging in the 

 customary references to extravasation, ecchymosis, and so forth, 

 -ind again, though it is, I believe, considered de ri<jv.eur hy your 

 true scientist to speak of colours as " belonging to the more or 

 less refrangible end of the spectrum," when one means that they 

 are blue, indigo, and violet, in one case, or red, orange, and yellow 

 in the other, yet we do sometimes hear a man of science by mistake 



• Mr. Foster mast excuse our relegating his ingenious theory to 

 Paradox Comer. 



speak of blue, red, or green, as the case may be, like other people. 

 The ca.se which I am going now to discuss is an instance in point. 



Before proceeding, however, directly to my theory, which relates, 

 let rao here mention, to the planet Mercury, I may say, 

 generally, that there appears to me something narrow, and, one 

 might almost say peevish, in the attempt made by too many 

 astronomers to restrict our ideas about other planets or suns by 

 what we know about our own earth and about oar own sun. Better, 

 as it seems to me, to indulge even in the freedom of imagination, 

 the unscientific licence, some would say, which gave birth to the 

 green-cheese theory of the moon and to other views not, perhaps, 

 absolutely defensible, than to be restricted within the narrow 

 limits of the known. Even men of profoundest scientific know- 

 ledge have admitted that "the known is little, the unknown is 

 immen.se." Where the field is so wide for guessing, why strive to keeji 

 the thoughtful student of scientific wonders confined painfully within 

 the narrow field of the known ? If we cannot enlarge our know- 

 ledge as we could wish, let us at least boldly widen our conceptions. 

 If we cannot prove the verdant caseity (or the caseous verdure) of 

 our satellite, let us not, therefore, be deterred from imagining that 

 in that remote world a state of things may exist of which we 

 terrene creatures, "limited little brutes" as we are (1 thank thee, 

 Miss Bella Wilfer, for teaching mo that word), can have but very 

 imperfect conception or no conception at all. 



(To he coiUinued.) 



s^fsqs^ij 



" Let Knowledc'e jn-ow from more to more."' — Alfred TE^•^•YSOX. 



leturs to tue (EUitor, 



Only a small proportion of Letters received can possihly he in- 

 serted. Correspondents must not he offended^ therefore, should their 

 letters not appear. 



All Editorial communications shoitld he addressed to the Editoe ok 

 Knowledge ; all Business comtnunications to the Pcblisheks, at the 

 Office, 7-i, Great Qiieen-street, TT.C. If this is not attended to, 



DEL.4Y"S AKISE FOR WHICH THE EDITOR IS NOT RESPONSIBLE. 



All Remittances, Chequct, and Post Office Orders should he made 

 payable to Messrs. Wyman & Sons. 



The Editor is not responsible for the opinions of correspondents. 



No COMMUNICATIONS ARE ANSWERED BY POST, EVEN THOUGH STAMPED 

 AND DIRECTED ENVELOPE BE ENCLOSED. 



THE FELLOWSHIP OF LEARNED SOCIETIES.— MEA- 

 SURING THE POWER OF AN EYE-PIECE. 



[674] — There are two of your "Answers to Correspondents" 

 with reference to which I should like to make a few remarks. The 

 first is that to " D. Q. J." (p. 500), concerning the Fellowship of 

 the Royal Astronomical Society, into which, as you but too truly 

 intimate, anybody can get who can obtain two or three people to 

 nominate him, and can afford to pay the fees. What is the conse- 

 quence ? Simply that the proprietors of middle-class schools of a 

 particular type, who want to write "F.R.A.S." after their names in 

 their advertisements, are perpetually being elected ; albeit their 

 knowledge of astronomy may be represented in many cases, alge- 

 braically speaking, as a — quantity. Speaking for myself, I think 

 that our bye-lavs should be altered so as ti> include some intellectual 

 test among the qualifications for Fellowship. A knowledge of the 

 chief numerical details of our own solar system ; of the first six books 

 of Euclid ; of the rudiments of algebra, trigonometry, and the power 

 to use a table of logarithms, would not be a desperately severe 

 criterion of fitness, and might spai'e us the scandal of any of our 

 confreres advertising themselves, iotidem verbin, as " eminent astro- 

 nomers," and compiling books on astronomy; when they could not 

 solve a common quadratic equation (to say nothing of summing a 

 convergent scries) to save their sotils alive. 



In the second place, I merely wish to say that the instrument 

 concerning which " H. S." (p. 500) has put a question is obviously 

 the very simple dynamometer invented by the Rev. E. L. Berthon, 

 of Romsey, Hants. 



A Fellow of the Royal Astronomical Society" 



