KNOWLEDGE 



nHEr( 



THE FACE OF THE SKY. 

 From Jdly 3 to July 17. 

 By "F.R.AS." 

 3nt indications of renewed solar activity in the ebape of 



grand spots render the son a very interesting object whei 

 ever the sky is clear. The face of the night sky will be found 

 depicted in Slap VII. of "The Stars in their Seasons." Twilight 

 persists all night long during the fortnight which these notes cover. 

 Mercury is an evening star, and, towards the end of the next four- 

 teen days, mav quite possibly be picked up with the naked eye 

 over the" W.N.W. horizon after sunset. Venus is an evening star, 

 too, and may certainly be seen in the same part of the sky. She 

 is still a very insignificant and uninteresting object in the tele- 

 scope. Jupiter may be caught pretty close to the horizon after 

 dusk; but at this time he is too low down for telescopic examina- 

 tion. The only phenomena of his Satellites theoretically visible are 

 the reappearance of Satellite IV. from eclipse at 8h. 28m. 40s. on 

 the 3rd ; the egress of the shadow of Satellite III. at 8h. 27m., and 

 the occultation of Satellite II. at 8h. 50m. on the 13th; the occulta- 

 tion of Satellite I. at 9h. 38m. on the 1-ith; and the egress of the 

 same satellite at 9h. 15ra. the ne.\t night. The observation of any 

 of these is, however, doubtful. Mars and Saturn are invisible, as 

 is Neptune too ; but Uranus may possibly be seen under unfavour- 

 able conditions as soon as it is sutficiently dark. The Moon enters 

 her last quarter 2SG minutes after noon on July 5, and will 

 be New at 5h. IS'Sm a.m. on the 12th. High tides may be ex- 

 pected about this date. No occnltations of fixed stars will take 

 place during the time which our notes cover, save one of Aldebaran 

 in bright sunlight at llh. 23m. 26s. a.m. on July 9. When they 

 begin, the Moon is in Pisces, across which she is travelling until 

 4 p.m. on the 6th, when she enters the N.W. corner of Cetus, 

 quitting it, however, for Aries at 2 o'clock the next morning (that 

 of the 7th). At Gh. 30m. a.m. on the Sth, she crosses the boundary 

 between Aries and Taurus. Her journey through Taurus occupies 

 her until 4h. 30m. p.m. on the 10th, at which hour she passes into 

 the narrow northern strip of Orion. By three o'clock the next day, she 

 has crossed this and emerged in Gemini. At 2h. 30m. p.m. on the 

 12th, she leaves Gemini for Cancer, and Cancer for Leo in turn at 

 1 a.m. on the 14th. She is travelling through Leo until 8 a.m. on 

 the 15tb, when she descends into Sextans, to re-emerge in Leo at 

 one o'clock the same afternoon. She finally leaves Leo for Virgo at 

 1 p.m. on the 16th, and is, of course, still in the last-named constel- 

 lation when these n 



jmbera of the Society of Telegraph Engineers, at the 

 of their president, Mr. Spagnoletti, Telegraph Super- 

 intendent of the Great Western Railwav, paid a visit to the 

 Swindon Works on Tuesday. Some five 'hundred members went 

 down by special train, and the visitors spent a most interesting and 

 instructive day. The works, as may be imagined, are of colossal 

 proportions ; they cover an area of thirty acres, and give employ, 

 ment to upwards of 5,000 men. No effort was spared, on the part 

 of the railway officials, to make the trip pleasant and profitable to 

 all who took part in it. The possible output is at the rate of one 

 engine, six carriages, and fifty trucks per week. 



We give the following from a paper entitled " On a variation in 

 the size of an image on the retina according to the distance of the 

 background en which it is seen," by Alfred Brothers, F.R.A.S., 

 which was read before the Manchester Literary and Philosophical 

 Society. " The effect on the retina when the eyes have been fixed 

 intently for a few seconds on a brightly-illuminated coloured 

 object is well known; the colour complementary to the one looked 

 at always appears when the gaze is removed to a colourless sur- 

 face. It is also a matter of common observation that when the 

 eyes have been directed to a bright light for a short time, the 

 image left on the retina as seen when the eyes are averted is dark ; 

 but if the eyes are rapidly opened and closed the image is still seen 

 bright. I am not aware, however, that it has ever been noticed 

 that this image varies in size according to the distance of the 

 background to which the eyes are directed. A circle of gas-jets, 

 perhaps, affords the simplest test. It will be seen after looking at 

 the circle of light for a few seconds — in some cases a more or less 

 lengthened gaze at the light is necessary, owing to the varying 

 sensitiveness of the retina— that, if the vision be turned to a dis- 

 tant background, the size of the image is instantly enlarged, and 

 then, if the eyes be directed to a near background, the image is 

 reduced in size. If any difficulty should be found in seeing the 

 reversed image of the gas-jets, it may readily be seen as a bright 

 object by rapidly closing and opening the eyelids. The effect is 

 the same as if the image were seen through a cone — the apex of 

 the cone being held close to the eyes. In other words, the effect is 

 the reverse of the ordinary rules of perspective." 



" Let knowledge grow from more to more." — Alfbed Tennyson. 



Only a fumll prnporlion of Letters reerircd ran posxilly le inserttd. 



CONVENTIONAL EVOLUTION. 



[1790] — Kindly allow me to make one or two suggestions upon 



what has been happily termed "Conventional Evolution." Every 



his doctrines; and sometimes it happens that such doctrines are 

 the least proven, as universal truths, by the master. This, I think, 

 has been the case with Darwin. He certainly relied very much upon 

 small variations in expounding his theory of " natural selection" ; 

 but it is doubtful whether he would have made them a sine qua 

 non, as his disciples do. Cataclysm and special creation were the 

 favourite hypotheses of our forefathers. We have now gone to the 

 other extreme, and nothing but a growth by infinitesimal grada- 

 tions will suit us. No kind of break is tolerated. It is assumed 

 that Nature is opposed to any sort of leaps, and, in accordance with 

 that idea, many of our present teachers point to an imaginary chart 

 of brutal ancestry descending by a slow unbroken chain to the parent 

 man — ape. The " missing links," of course, may yet be found, bnt 

 till they are why draw so largely upon imagination ? Has Natnre 

 no phenomena by which the breaks can be explained ? Does she 

 never pass abruptly from law to law ? The anther of the " Vestiges" 

 made such a suggestion, but no one, it; seems, has ever followed it 

 up. In chemistry we pass from one substance to another by 

 sudden steps. You cannot link calomel to corrosive sublimate by 

 gradations of chlorine. The diamond, too, enters suddenly under 

 the control of laws which have no apparent concern with common 

 charcoal. But leaving the inorganic world on one side, what are 

 we to say to the leap Natnre makes in creating a Shakespeare or a 

 Beethoven ? Can we lead up to them by a slow ascending series 

 of their ancestors, or do they suddenly appear, like Minervas, fnlly 

 formed ? 



I had something to say about Darwin's law of correlation being 

 so much neglected of late, but I am afraid I have already taken np 

 too much space. Gamma. 



SPIDER. 

 [1791]— If one may hazard a conjecture on so short a descrip- 

 tion, the spider referred to by " Hallyards " is perhaps Thomisus 

 ahlrei-iatus. This is a buff-coloured spider with the body abruptly 

 bent down behind, and with an angular projection on each side of 



the upper part at the edge of the bend. But it has/i-c small pits 

 on the upper surface. Some members of this genus are found in 

 flowers, and 1 have seen one so closely resembling in colour the 

 flower (a composite one) amongst whose florets it was lying in 



