164 



♦ KNOWLEDGE ♦ 



[Dec. 23, 1881. 



forth. Mr. Banyai-d, we arc sure, had no thoughl of citing Mr. 

 Baxcndcll as an example of the objectionable clasa of iicicncG 

 workors (or nithcr uf iicrsoiis who wout to work ncioiicc) to whom 

 ho n'forrod. Mr. liaiiyanl's lutter has been rof^ardud by quite a 

 large uunibcr of corrcspondcuta as unduly considerate towards pnra- 

 doxers, while othei'S consider it aa very gentle towards them, but 

 not unwarrantably so. UlCllABb A. Fuoctou. 



SIE KICUABD PHILLIPS. 



[137] — "Delta" offers to send weekly paragraphs, pirinR start- 

 ling and important theories propounded by Sir Richard Phillips, 

 which he believes would be read and studied with profound interest 

 by readers of K.vowr-EPGE. After reading the specimens " Delta" 

 forwards, I decide that only one paragraph relating to Sir B. Phillips 

 shall appear in these columns so long as they are under mj- charge. 

 It is not one of his own writing, but by the late Professor De 

 Morgan, and runs thus : — 



" Sir Eichard Phillips had four valuable qualities — honesty, zeal, 

 ability, and courage. Ho ap])Ucd them all to teaching matters 

 about which he knew nothing, and gained himself an uncomfortable 

 life and a ridiculoiis memorj-." Ricii.MtD A. Pkoctor. 



RETROGRADATION OP A PLANET. — ORRERY. — SOLAR 

 HEAT. — ASTRONOMICAL SLIDES. — DENSITY OF NEP- 

 TUNE. —VULCAN.— THE GRAVITY OF SIR R.PHILLIPS. 

 -PLANETARY RINGS. — THE GREAT BEAR. — SIRIUS 

 AND ORION.— ALGOL AND MIRA.— STAR LETTERS AND 

 NUMBERS. — NEW STAR IN CASSIOPEIA. —A'ENUS IN 

 SUNSHINE. — VELOCITY OP LIGHT. — EVOLUTION. — 

 RAINBOW. — SOLAR STORMS. — ANTIQUITY OF THE 

 PYRAMIDS. — MENTAL PHYSIOLOGY.— THE ANTIQUITY 

 OF MAN.— TOADS. 



[138] — As no one, so far, appears to have replied to the Query 

 (17) of " Astronomicus," on page 60, perhaps 1 mar say, shortly, 

 that the seeming retrogradation of a planet is a differential phe- 

 nomenon, arising from the fact that the earth moves less rajiidly in 

 her orbit and describes a larger ellipse than the interior planets 

 Mercury and Venus ; and more rapidly than those exterior to her — 

 Hars, Jupiter, .Sattirn, Uranus, and Nei)tune, whose orbits must 

 obviously increase in size as they recede from the sun. If " Astro- 

 nomicus" ^vill describe a series of concentric circles to represent 

 the paths of the planet.i, and suppose them to travel round such 

 ciixles in a direction opposite to tliat of the hands of a watch, and 

 at rates proportioned to their periodic times (to be obtained from 

 any Primer of Astronomy whatever), he will soon see how, taking 

 the case of Mars, for example, when the eaith is between that 

 planet and the sun, she, as it were, overtakes him. Evidently in 

 doing so Mars will appear to go back, as it were, among the infinitely 

 distant stars; as will, in a similar manner, the planets outside him 

 when in and near opposition. So far the appearance of retrogi-ada- 

 tion may be called subjective. I may now add, what I abstained 

 from saying in connection with Mercur)' and Venus, for fear of eon- 

 fusion, that they have also an objective movement of retrogradation, 

 when they come between the sun and the earth, as your correspondent 

 may see from his own figures. Mars is the planet whicli describes 

 the largest retrograde arc, the reason for which will also bo appa- 

 rent from his diagram. 



" Vulcan " (query 20, p. SO) may see an orrery at South 

 Kensington. 



If "Warmus" (query 30, p. 101) possesses a pair of compasses, 

 he may clear up part of his difficulty by constructing a simple 

 figure ; or he may even do so by tlie aid of a bronze halfpenny. 

 Let him, then, describe a. circle one inch in diameter, and from the 

 top and bottom of this draw two parallel straight lines, between 

 wliich he may rule as many more as he likes strictly parallel to 

 them. These he may take to represent the sun's rays. Now, let 

 liim get a strip of card one-inch long, and hold it square across his 

 series of lines. Obviously they will all fall upon it. If, .however, 

 he holds it slantingly across them, ho will see that fewer and fewer 

 of them touch it as its obliquity increa.'-cs. Now this is just what 

 happens on tho earth. Within the tropics, where the sun is always 

 somewhere overhead, all his rays tall squaie to the obscn'er's hori- 

 zon. Where, however, as in high northern and southern latitudes, 

 the sun never, even at noon, reaches any great elevation above the 

 horizon, his rays necessarily fall obliquely, and we receive com- 

 paratively few of them. With reference to the concluding i>art of 

 " Warmus's" question, the gentleman who gets tanned by the sun 

 in a tropical country has his complexion spoilt by the direct and im- 

 mediate action of the sun on the re(e mucosum, or under layer of 

 the skin. It is this that sunlight enters directly, and not the earth 

 first ! 



It " C. J. S. " (query 33, p. 101) only wants bia slidei for one 

 night, he will find that patent plate gloss, dciUMily smoked by burn- 

 ing camphor, will give him an absolutely opaque ground, on which 

 very effective diagrams may be made by the aid of etching and 

 sewing needles and compasses with a needle point. He must gnm 

 a little bit of paper on before smoking hia slide, as a centre for one 

 leg of the com|)a88e8 to rest on, as otherwise they slide about the 

 glass and make undesirable lines and scratches. 



Assuming that wo arc looking at the outline of the solid body of 

 Neptune, then I may tell " S. S. S. S." (query 38, p. 101) that bil 

 density must be something like 096; that of water being 1. Only 

 one satellite is known. Its period is od. 21 h. 3 m. 



In answer to " S. .S." (query 41, p. 101), there is a practical con- 

 census of opinion among astronomers that Vulcan has no existence 

 whatever. I am not denying that there may be a planet, or planets, 

 between Mercurj- and the Sun, but the pseudo-observation of Les- 

 carbault was suOiciently definite to enable computers to calculate 

 the orbit of the alleged body. This having been done, it niu»( havs 

 reappeared on tho sun's disc on several occasions since, when the 

 most skilled observers, employing powerful instruments, have 

 wholly failed to see anything. It is the "Mrs. Harris" of the 

 solar system. 



" Meter" (query 45, p. 101) appears to be unaware that scientific 

 men pay about the same kind and amount of attention to the lucu- 

 brations of Sir Richard Phillips that they do to those of, say, 

 "Parallax," or Mr. John Hampden. 



The same correspondent (succeeding query) should buy and read 

 " Saturn and its System," by the Editor of this journal. 



Mr. St. Clair (query 57, p. 101) will find that the principal stars 

 in the Great Bear all set in latitudes below 25° Nortli. The second 

 part of his query is, in one sense, meaningless ; because in the 

 case of a circum-polar constellation, what is east below the Pole, 

 becomes west above it, and I'ice-versi ; but, in the sense that the 

 right ascension of Benetnasch exceeds that of Dubhe by some 

 2 hours 47 minutes, of course the latter star is the westernmost, 

 as by " longitude " your correspondent obviously means right 

 ascension. I may say that Ursa Major straggles over six hours in 

 the sky, as nearly as may be from o on one side to 2 1830 on the 

 other. I quite fail to understand the meaning of the constellation 

 having " a cycle of 2,700 years ; " nor am I in any better position 

 to clear up the diiiieulty as to the supposed connection between 

 Sirins and either Ursa Major or Minor. 



In answer to query 58, p. 102, Sirius was one of Orion's hounds, 

 but that it was ever placed on the " shoulder" of the giant is news 

 to me. 



The great comet spoken of by "S. C. H. " (query 61, p. 102), 

 has no other designation than comet b, 1881. Its orbit was seem- 

 ingly parabolic, and the parabola — as " S. C. H. " doubtless knows 

 — is a curve which does not return into itself. 



'■ S. C. H." (query 62, same page) will find Algol marked on the 

 map on p. 97. It is in tho head of Medusa. 



" F. H. S." (query 63, p. 102) asks when Algol and Mira are at 

 their brightest ? In the case of the first-named star, he should 

 rather ask of the date of its minimum, inasmuch as itshines as a 

 star of the second magnitude for about 2d. 13h., diminishes to the 

 fourth in tliree or four hours, remains as a fourth magnitude for 

 about twenty minutes, and again increases iu brightness until it 

 regains the second magnitude. It passes through the entire cycle 

 of its changes in 2d. 20h. 48m. 553. For its next minimum, 

 " F. H. S." must really watch for himself. Mira Ceti should attain 

 its next maximum about June 16 or 17, 1882. 



Stars, I may say, in answer to query 64 (p. 102), are both 

 lettered aud numbered in their order of right ascension. 



By the periodical star, concerning which "F. H. S." puts hia next 

 query (65), his informant pi-obably meant to imply that if the one 

 which blazed out somewhere about RK Oh. 19m., and Dec. 63° 24 'N. 

 in November, 1572, was identical with those which appeared in or 

 near the same spot in 945 and .1264, it may possibly soon reappear 

 now. 



Next, I would tell him (query 66) that Venus is always visible to 

 the naked cyo in bright sunshine to anyone who knows where to 

 look for her — at and about the time when tho Xaulical Almanac 

 gives the intimation " ? at greatest brilliancy." 



It may be worth while to remark, in connection with letter 100 

 (p. 116), that the latest and best determination of tho velocity of 

 light, gives it as 186,380 miles a second. Hence, as the pace of the 

 fastest express never exceeds sixty miles an hour, it must travel 

 jijjth of a mile in a second, so that the velocity of light must be in 

 reality about 1,118,000 times that of the train. 



Mr" Mitchell (letter 107, p. 117) might advantageously study Pro- 

 fessor Huxley's lecture on the convincing evidence, from fossil 

 remains, of the direct descent of the horse from the Hipparion, 

 delivered before the Zoological Society iu December, 18S0. 



'■ G. S. M." (query 67, p. 122) should readTyndall's " Six Lectures 



