[From the "Monthly Notices" of the Royal Astronomical Society. Vols. 31-32, June, 1872]
On May 1, 1871, I had a good view of the planet Venus, but I could not at first see her to my satisfaction as her light was so bright. She had more the appearance of a miniature sun than a star; but I put a diaphragm of blackened card in the eye-piece, and made a small hole through its centre with a piece of hot wire. I found this arrangement keep out to a great extent the glaring rays. I also sometimes used a slip of slightly tinted glass in front of the eye lens; this enabled me to bring the planet entirely under subjection. Her shape was that of the moon when a little more than half full. I distinctly saw a dull, cloudy-looking mark along her bright limb, curving round parallel to it, and extending nearly across the disc, each end terminating in a point; joining this at the eastern extremity was another and darker mark of a club shape, its small end joining the point of the mark previously described. I watched these marks for half an hour. I saw some marks again the next evening, but before I could examine them the planet was hidden behind some clouds. On May 6, at 7.45 p.m., there was a cloud-like mark extending straight across the disc, and a club-shaped mark nearly in the centre, with its small end nearly touching the straight cloud. On the western limb another dark mark had made its appearance; it was not quite so large as the other, and it was not club-shaped; but its sides were parallel to each other till they approached the straight cloud, when they appeared to divide, each side curving round away from the other. I took much interest in watching these spots, as I had read that it was very doubtful whether any marks had ever been seen on this planet. I called several men to look at them, and they were able to describe them, although they had no previous knowledge or idea of what they were likely to see. One man was very confident it was the moon he was looking at, but when I pointed out to him that the moon was not in the neighbourhood, he said he thought it was the moon, because he could plainly see the dark patches on its surface.
On May 13, at 7.30 p.m., there was a dark mark of a pear shape, extending from near the western edge to two-thirds the distance across the bright disc. This mark was not so dark as those seen on the 1st and 6th, but it was much larger.
On July 28, at 8 p.m., there were visible five dusky marks along the planet's terminator, and one nearly in the centre of the crescent, but they were not so well defined as those before described; but what seemed to me more remarkable was that the southern horn was rounded off considerably, whilst the northern horn was quite sharp, and ran out to a very fine thread-like point.
On October 13, at 5.45 a.m., I saw Venus as a beautiful little crescent. She was well defined, and both horns were as sharp as the finest pointed needles. I think I detected a dusky cloud-like mark about half way from the centre to the northern horn; but I am not quite sure about this as I had to leave my telescope before I could complete my sketch.
On October 25, at 8.10 a.m., I was gratified with a sight which I had waited for and longed to see for many years; that was to have a good view of Venus by daylight. I now had the longed-for opportunity, and it turned out as I expected. The superior light of the sun overcame that of the planet to such an extent that I was able to see her better than I had ever seen her before. I could now plainly perceive the jagged nature of the terminator, the unevenness of which could not be mistaken; but what was very remarkable, the northern horn was bent in towards the centre of the planet; it appeared as if a notch had been cut in the inside, and a slice cut off from the outside.
I have no idea what was the cause of this appearance; I had never seen it so before, neither do I recollect ever having read of such a phenomenon. I did not perceive any markings on this occasion, but there was a kind of haziness along the whole length of the terminator; but I considered this at the time to have belonged to the terminator rather than to any markings on the disc. The terminator on this occasion was inky black.
On November 9 I saw Venus every half hour during the day up to one o'clock. I made a sketch at 12.20 p.m. I could now distinctly see the jagged terminator; the nature of which was so much like that of the moon as it was possible to conceive; except that if we compare the moon's terminator to a piece of network, that of Venus would be represented by a piece of fine lace. I could also see some thin, cloudy marks on her disc. The southern horn was very sharp; the northern one was a trifle rounded.
I saw Venus on February 5, 1870 (a few days before her inferior conjunction with the sun), and the bright part was an exceedingly beautiful fine crescent; but I and several other people could see the whole body of the planet in the same manner as we see the dark limb of the moon when Earth-shine is falling upon it; but I did not make any sketch at the time.
I have observed Venus a great many times besides those mentioned above, having made it my special work to do so, and have on several occasions strongly suspected markings to be visible; but I have not mentioned them, and have only described those times upon which I have no doubt of what I had seen.