It is an interesting fact that we owe a large proportion of our knowledge of planetary detail to the work of enthusiastic amateur observers. In this Society, indeed, nearly all the best observational work was done by the non-professional class; and when, as the result of their systematic and painstaking work, they noted on their planetary drawings some lines or markings which had not previously been recorded, one would have thought their original work would have been commended. It was, however, not unusual in such cases for a professional to rise and calmly declare that the new markings were only illusions, such as he had often predicted would be claimed as discoveries. Thus the amateurs were kept in their proper places; but the professionals did not always prove to be correct in their strictures and pronouncements. In these circumstances, I did not expect much credence to be given to anything fresh that might be stated in my address, and therefore I rather demurred to Sir Lockesley's proposal. He, however, made such a personal matter of it that, as he was an extremely able man and a good fellow, I at last consented to do as he wished. M'Allister accompanied me to the meeting and sat among the audience. After a few introductory remarks from Sir Lockesley, I gave my address, which lasted about half-an-hour; but it was received even more chillingly than I had anticipated, and the few comments made by the members were nearly all indicative of scepticism of my statements and unbelief in my _bona fides_. A scientific audience is usually rather cold and unenthusiastic; but, in the present case, except for one or two isolated hand-claps, the vote of thanks was allowed to pass _sub silentio_. Sir Lockesley, of course, could not help this, and I saw that he was much annoyed at my reception. The meeting then split up into groups, lingering here and there to discuss my statements as they moved toward the door; and M'Allister told me that, as he stood near a group, he heard one man exclaim, "It's all arrant nonsense! five minutes with my 12-1/16-inch reflector would convince any sane man that there are no fine lines to be seen on Mars, because none exist!" This brought a murmur of assent; then some one else said, "Well, I certainly see some of the lines with my 7-1/2-inch, but regard them as illusions"; and he also received some support. Another man then spoke up, remarking, "My experience does not agree with yours, gentlemen, for when I used a 6-inch refractor I could see some of the lines, yet felt doubtful of their actuality; but since I have used a 12-inch reflector my opinion has entirely changed. The lines are visible whenever the atmospheric conditions are favourable, and are seen with so much certainty that I have long abandoned my doubts of their representing real markings!" "Hear, hear!" said several, "and in a clearer atmosphere you would see still more!"