March I, 1900.] 



KNOWLEDGE. 



61 



Bewick Swaxs in Suffolk. — On February 3rd, a 

 keeper informed us a herd of wild swans were on Bonacro 

 Broad, so my host, his son, and myself went down there 

 with guns and opera-glass js. We counted seven, and as 

 one appeared to be wounded we shot it. It was 

 Bewick's, and measured 6 feet 2 inches across wings. 

 4 feet total length, but only weighed 9 lbs., cwing no 

 doubt to having in some way been wounded. Until 

 we disturbed them they were making a loud, short. 

 barking noise, and pulling up weeds from tht bottop. 

 of tlie broad which the coots around them seemed to 

 enjoy very much. Of course the smaller size of Bewick s 

 swan will always define it from the whooper, but when 

 only one of the two species is to hand, .and no scales, 

 the orange patch on the base of the bill, stopping at 

 the nostrils in Bewick's, and continuing on, in an 

 oblique line, in the whooper, will readily show tin 

 difference. I have noticed that paintings represent 

 both these swans with black marginal rims to their 

 eyes, like the mute swan, whereas they arc really 

 orange. — Jos. F. Green. 



Kite in Kent. — On the 23rd of November, 1899, a 

 kite. Milvus regalis, 6 feet across the wings, was 

 shot by a keeper at Swinyficld Miller, 2i miles from 

 Folkestone. It was on a hare. It had been noticed 

 in the locality for about a month, and mistaken for an 

 eagle. — Jos. F. Green. 



YeUow-hilled Cuckoo (Cocci/zus americanus) in Walfs. (Ibis, 

 January, 1900, p. 219.) Mr. George Dickiuson, in a letter to the 

 Ibis, sa_T9 that a specimen of this Amerioau species was picked up 

 dead at Craig-y-dou. on the sliores of the Menai Straits, on November 

 10th, 1899. This is the seventh occurrence of this species in various 

 parts of the British Islands, but it is scarcely possible that any of 

 them arrived here from America of their own accord. They have 

 all, witliout doubt, escaped from confinement, probabh' on board sliip. 



Rough-legged Buzzard near Londonderry. (Irish NaiuraUst, 

 February, 190«_), p. 50.) Mr. D. C. Campbell records that a male 

 of this species was shot by Mr. W. Kilpatrick, at Campsic, near 

 Londonderry. This is apparently its second occurrence in Co. Dcrry, 

 and tlie eleventh in Ireland. 



All contributions to the column, either in the way of notes 

 or photographs, shouhi he foruardcd to Harry F. Witherby, 

 at 1, Eliot Place, Blackheath, Kent. 



ASTRONOMY WITHOUT A TELESCOPE. 



By E. Walter Maunder, f.r.a.s 

 XL— THE ZODIACAL LIGHT. 



On the strict principle of order, the Zodiacal Light 

 should not come first amongst the subjects which I 

 propose to take up in this series of papers, yet as the 

 time of the year has come round when the Light is best 

 seen it may be well to neglect the question of strict 

 order and give it precedence. 



The earliest English description of the Zodiacal 

 Light of which I know was given by Dr. Childrey at 

 the end of his Britannia Baconica, published in 1660. 

 It is as follows : — • 



"There is a thing which I must needs recommend to the 

 Observation of Mathematical ilen, which is that in Fehruarxj and 

 for a little before and a little after that Month (as I liave observed 

 several Tears together) , about 6 in the Evening, when the Twilight 

 has almost deserted the Horizon, you shall sec a plainly discernible 

 way of the Twilight striking u]) towards the Pleiades or .Seven 

 Stars, and seeming almost to toudi tlicm. It is to be observed anv 

 clear Night. Tliere is no such AVay to be obser\ cd at any other 

 time of the Year that I can perceive, nor any other Way at that 

 time to be perceived darting up elsewhere. And I bidicve it hath 

 been and will be constantly visible at that time of the Year." 



This description of the Zodiacal Light is quite suffi- 

 ciently accurate for our ordinary English experience. 



In the tropics, however, it is seen far more constantly, 

 and attains a brilliancy pnd distinctness of which we 

 seldom have any example bcio There not only during 

 spring, but more or less di>iing the whole year, if the 

 western sky be watched :<ftcr sunset, a.s the twilight 

 fades out, it will be seen that the twilight which at 

 frst seemed to be a pretty regular .nrch in the west, 

 begins to show a tongue of somewhat greater brightness, 

 which becomes clearer and clearer as the background 

 of the sky around becomes darker, until at length 

 it stands out defined as a great nebulous patch of ligiit. 

 troadest and brightest near the horizon and f.-icling 

 gradually away to the right and left and towards its 

 apex. At its brightest part, and when best seen, it 

 often much out«shincs the Milky Way by as much 

 perhaps as a couple of magnitudes — that is to say, 

 about six times; or about as much brighter than the 

 Milky Way as the latter is in excess of the average 

 brightness of the sky. But such a degree of brightness 

 is confined quite to the centre of the light and to the 

 portion nearest the sun; its borders melt indefinitely 

 away until they are no brighter than the background 

 of the sky. 



The shape of the Zodiacal Light varies. It is broadest 

 close to the horizon, where it may be as wide as 2.5° 

 or even 30°, and tapers somewhat quickly at first. At 

 60° or 70° from the sun, it has become much naiTower, 

 and its edges, so far as they can bo discerned, arc nearly 

 parallel. 



It is easy to see why this beautiful and mysterious 

 object is so much better seen in the tropics than in the 

 temperate zone. The twilight is so much moi-e pro- 

 longed in the latter, and the Light is of so elusive a 

 character, that a throe days' old moon is sufficient to 

 blot it out. It cannot, therefore, be seen here ncarlv 

 so soon after sundown as in the tropics, partly because 

 the ecliptic with which its axis nearly coincides is 

 lower in our skies than in equatorial regions, and 

 partly because our twilight is so much more prolonged. 

 If we take it that it is aot until about an hour and a 

 half to two hoiu's after sunset that we can see the 

 Light in this country, then at the end of February or 

 the beginning of March we shall have the point of 

 intersection of the ecliptic and equator upon the 

 horizon just about the time when the Light is begin- 

 ning to show itself. And. as the accompanying 



Inclination of tlie Ecliptic when tlie Kquinoctial and Solstitiid Points 

 are on the West Horizon. 



diagram will show, the angle which the ecliptic makes 

 with the horizon is greatest at this time of the year; 

 so that the Zodiacal Light rises up more abruptly into 

 the sky than at any other time, and its briglitness is 

 therefore least affected by Uio absorption of the lowest 

 strata of our atmosphere. 



Although the Zodiacal Light has been more or less 

 under observation for some three centuries, — the great 

 Kepler having carefully observed it, with the result 

 of convincing himself that it was the atmosphere of 



