March i8, 1875 J 



NATURE 



389 



cleaved up in time for tlie observation of the important internal 

 contact. The atmosphere was splendidly 'steady' in con- 

 sequence of ihe previous fall of rain, and the effect of this was 

 that the definition of the phenomenon was very distinct. There 

 was no haziness or appearance of a ' black drop.' The contact 

 was clear and tangential, and altogether free from the expected 

 interferences witli a good observation. During the contact and the 

 following few moments, the photoheliograph was set to work, and 

 numerous photographs of the ingress were obtained. Fhey were 

 taken rapidly at about two-second intervals, and about fifty were 

 .secured. The great telescope was used solely for photographing, 

 in addition to the heliograph, but unfortunately it could not be 

 brought into position quickly enough for photographs of the in- 

 gress to be taken by it, though it was used very effectively further 

 on. The clouds then, as if they had just parted to allow of an 

 observation at the critical moment, closed again over the sun, and 

 its face remained obscured, with only occasional breaks, till be- 

 tween two and three o'clock. These breaks were availed of to 

 obtain micrometric measures of the planet, which was now well 

 on the sun's disc, and also to take photographs with the photo- 

 heliograiih and the great telescope, which were very successfully 

 obtained. Between two and three o'clock the weather began to 

 clear up a little, and the observers were able to go more leisurely 

 to work. The photogi'aphing went on well, though with several 

 interruptions from passing clouds. The internal contact at egress, 

 a very important point, was also observed, very satisfactorily, 

 although the atmosphere was a little more disturbed than during 

 the internal contact at ingress, and 'there was observed a faint 

 attempt at that appear.ance known as the 'black drop,' and a 

 slight hazy ligament. For these reasons the internal contact at 

 egress was not quite so satisfactorily observed as that at ingress, 

 though a very good observation was made. During the egress a 

 satisfactory serits of micrometric measurements was made of the 

 ' cusps,' and a rapid series of photographs was also obtained at 

 two or three seconds' interval by means of the photoheliograph. 

 The actual first internal contact was later than it was computed 

 it would be by 3m. 13s. The first internal contact occurred at 

 forty-five seconds after noon. The tabular time was i ih. S7m. 32s. 

 The internal contact at egress occurred at 3h. 29m. 5s., or 

 im. 3 IS. after the computed time, which was set down in the 

 tables at 3h. 30m. 36s. 



"Two hundred Janssen photographs were taken, and on dere- 

 lopment they were found to be as satisfactory as could have been 

 expected, considering the frequent interruptions from clouds, and 

 they will probably furnish some very important data. Besides 

 these, thirty-seven photographs were taken with the great tele- 

 scope and forty-seven with the photoheliograph. These were 

 only taken when the sun was unobscured. 



"Mr. Russell, the Government astronomer at Sydney, reports 

 as follows : — ' Very fine at Sydney, also Woodford and Goul- 

 burn, and, I believe, Eden (Twofold Bay.) I obtained a good 

 many photographs. No black drop. Contacts not obtainable 

 to a fraction of a second.' Mr. Russell also states that a beau- 

 tiful halo was visible around Venus (indicating the atmosphere), 

 before the planet was wholly on the sun. The Government 

 parties have a total of 1,300 photos. 



" The German party at the Auckland Islands have been heard 

 of; from ten minutes after ingress the weather was very fine, and 

 1 50 photographs were taken. 



" Mr. EUery, in a paper read before the Royal Society 

 of Melbourne, has given some information of great im- 

 portance from a physical point of view, consisting of a 

 compilation of all the observations of this nature which 

 have been forwarded to him : — 



"Mr. Anketell M. Henderson, observing with a Browning 

 8i-inch Newtonian, writes : — 



"'It cleared about 11.40, and I got my first observation. 

 Definition perfect ; not the slightest tremor. At 11.53 or there- 

 about I was surprised by seeing the surface of Venus, outside the 

 sun, distinctly visible on a faint phosphorescent-looking back- 

 ground ; it remained visible for about forty-five seconds, when 

 clouds interfered.' Mr. C. Todd, of Adelaide, observing with 

 an 8-inch iclractcr by Cooke and Son, remarked : ' For some 

 time after internal contact at egress the portion of the planet 

 which had moved off the sun was distinctly visible, appearing as 

 though seen through a nebulous aid luminous haze of a purplish 

 hue, extending beyond and around the edge of the planet, and 

 inclining to violet towards the sun.' He had received no other 

 notes of the visibility of the disc of Venus outside the sun's disc 



at egress, and he had been unable to get any trace of it himself, 

 although the sky was clear and he looked for it. At Glenrowan 

 the Transit was seen earlier than at Melbourne, and when the 

 phnet was about two-thirds on the sun Mr. Gilbert remarked, 

 ' N.W. limb slightly luminous.' He then came to the .appear- 

 ance presented at internal contact, of which he noted as follows : 



' This phase was remarkably well seen, and was almost tangential 

 and free from any haze, ligament, or other disturbance. The 

 sky remained clear in the neighbourhood of the sun till after 

 internal contact was well over. About half-past two, before con- 

 tact, limb of sun appeared to bulge out so as to embrace Venus, 

 the outwardly bent cusps continuing around Venus like a thread 

 of silver. Occasionally a slight flicker between the limb of 

 Venus and sun visible, then a hazy junction like thin smoke 

 appeared, and finally a very faint smoky thread appeared to join 

 the thin edges. This suddenly disappeared at oh. im. 9'4s , 

 iMclboume time.' Mr. White's obsen'ations gave almost similar 

 results. At Mornington the late Prof. Wilson noted a ' fluffy 

 connection,' which is undoubtedly the same phase already noted, 

 viz., 'smoky connection.' At the final junction the sun's edge 

 was very tremulous, but the sky was quite clear. Prof. Wilson 

 stated of this phase that ' the sun's edge was boiling. Venus 

 did not look round, but as you might imigine a spherical balloon 

 not quite blown up ; the edge looked crumpled. A small dark 

 object was seen flickering backwards and forwards between 

 Venus and the edge of the sun. This increased, and there was 

 no other phase to which 1 could attach a definite time.' At 

 Sandhurst, Mr. Moerlin, observing with a 6.^-inch refractor, 

 remarked : ' As the planet moved gradually near the sun's 

 limb at exit, the sun's limb and planet appeared sharp and well 

 defined, and the streak of light between the two was distinct and 

 unmistakable. As it came nearer and nearer the same appear- 

 ance was witnessed without any change whatever. The streak 

 of light became smaller, and all at once a sort of triangular- 

 shaped connection between the two was observed, an appearance 

 which I have seen with the artificial transit, but 10 a more limited 

 extent, the base of the triangle on the sun's limb, the apex on 

 the planet. The time when this phenomenon first appeared was 

 3h. 26m. 54 'jS. The planet every once in a while jumped off 

 the apex of the triangle, and the rim of the sun's disc could be 

 diitinctly seen between the two, the distance, however, between 

 the triangle and the planet when jumping, growing less. Tiie 

 jumping or separating of the apex of the triangle and the planet 

 cessed a few seconds before what I considered tangential con- 

 tact.' Mr. Todd says, respecting this phase, that ' it was quite 

 clear at egress, which was well observed ; no black drop, but 

 the continuity of the sun's disc was first broken by an exceed- 

 ingly fine black line. The planet was seen to be slightly dis- 

 turbed, the outline of the ball being apparently drawn out into a 

 thin band.' With respect to an atmosphere surrounding Venus 

 and the presence of a satellite, some of the observers had noticed 

 towards the centre of Venus a light which condensed almost to 

 a bright spot ; and the Rev. Mr. Clarke, of Williamstown, ob- 

 served a brownish orange halo surrounding Venus, and some 

 others had observed a coloured light, though the difference of 

 the lint was no doubt due to the eye-pieces used. He himself 

 observed a blue light surrounding the planet, and made a careful 

 scrutiny of it. He also called Mr. White and several others to 

 observe, and they all saw it. He also noticed the granulated — 

 or, as it was called, willow-leaved — appearance of the sun, which 

 was very distinct, but approaching the planet presented a blurred 

 appearance. With respect to the bright spot noticed in the centre 

 of Venus, the same phenomenon was observed in the centre of 

 Mercury during the transit of that planet. 



" It has been suggested that all the observing parties at 

 stations in or near Australia should meet about February 

 in Melbourne, and compare their observations. Similar 

 observations to those which have evidently attracted the 

 attention of Mr. EUery in a marked degree were perhaps 

 made under the best possible conditions by Mr. Hen- 

 nessey, at a height of between 7,000 £.nd 8,000 feet in the 

 Himalayas, and by other observers in India." His obser- 

 vations have been communicated to the Royal Society, 

 and will be found in Nature, vol. xi. p. 318. 



" We must wait for some time for the final determination 

 of the sun's distance as deterinined by the Transit obser- 

 vations, but no time need be lost in fully discussing the 

 various physical questions raised, in order that we may 

 be fully prepared for the Transit of 1882." 



