The object of this excursion was to visit the remarkable series of grooved and scratched rocks which had been discovered[note: They had been first seen, some twenty years before, by Sir James Hall, one of the geologic lights of Edinburgh.]

on the western edge of the cliff-like boundary of Corstorphine Hill. The glacial origin of these groovings on the rocks was then occupying the attention of geologists. It was a subject that Robert Chambers had carefully studied, in the Lowlands, in the Highlands, in Rhine-land, in Switzerland, and in Norway. He had also published his Ancient Sea Margins and his Tracings of the North of Europe in illustration of his views. He was now enabled to show us these groovings and scratchings on the rocks near Edinburgh. In order to render the records more accessible, he had the heather and mossy turf carefully removed -- especially from some of the most distinct evidences of glacial rock-grooving. Thus no time was lost, and we immediately saw the unquestionable markings. Such visits as these are a thousand times more instructive and interesting than long papers read at scientific meetings. They afford the best opportunity for interchange of ideas, and directly produce an emphatic result; for one cannot cavil about what he has seen with his eyes and felt with his hands.

We returned to the city in time to be present at a most interesting lecture by Hugh Miller on the Boulder Clay. He illustrated it by some scratched boulders which he had collected in the neighbourhood of Edinburgh. He brought the subject before his audience in his own clear and admirable viva voce style. The Duke of Argyll was in the chair, and a very animated discussion took place on this novel and difficult subject. It was humorously brought to a conclusion by the Rev. Dr. Fleming, a shrewd and learned geologist. Like many others, he had encountered great difficulties in arriving at definite conclusions on this mysterious subject. He concluded his remarks upon it by describing the influence it had in preventing his sleeping at night. He was so restless on one occasion that his wife became seriously alarmed. "What's the matter wi' ye, John? are ye ill?" "On no," replied the doctor, "it's only that confounded Bounder Clay!" This domestic anecdote brought down the house, and the meeting terminated in a loud and hearty laugh.

I, too, contributed my little quota of information to the members of the British Association. I had brought with me from Lancashire a considerable number of my large graphic illustrations of the details of the Moon's surface. I gave a viva voce account of my lunar researches at a crowded meeting of the Physical Section A. The novel and interesting subject appeared to give so much satisfaction to the audience that the Council of the Association requested me to repeat the account at one of the special evenings, when the members of all the various sections were generally present. It was quite a new thing for me to appear as a public lecturer; but I consented. The large hall of the Assembly Rooms in George Street was crowded with an attentive audience. The Duke of Argyll was in the chair. It is a difficult thing to give a public lecture especially to a scientific audience. To see a large number of faces turned up, waiting for the words of the lecturer, is a somewhat appalling sight. But the novelty of the subject and the graphic illustrations helped me very much. I was quite full of the Moon. The words came almost unsought; and I believe the lecture went off very well, and terminated with "great applause." And thus the meeting of the British Association at Edinburgh came to an end.

This, however, was not the end of our visit to Scotland. I was strongly urged by the Duke of Argyll to pay him a visit at his castle at Inverary. I had frequently before had the happiness of meeting the Duke and Duchess at the Earl of Ellesmere's mansion at Worsley Hall He had made us promise that if we ever came to Scotland we were not to fail to pay him a visit. It was accordingly arranged at Edinburgh that we should carry out our promise, and spend some days with him at Inverary before our return home. We were most cordially welcomed at the castle, and enjoyed our visit exceedingly. We had the pleasure of seeing the splendid scenery of the Western Highlands the mountains round the head of Loch Fyne, Loch Awe, and the magnificent hoary-headed Ben Cruachan, requiring a base of more than twenty miles to support him, -- besides the beautiful and majestic scenery of the neighbourhood.

But my chief interest was in the specimens of high geological interest which the Duke showed me. He had discovered them in the Island of Mull, in a bed of clay shale, under a volcanic basaltic cliff over eighty feet high, facing the Atlantic Ocean. He found in this bed many beautifully perfect impressions of