While visiting, in 1861, the auriferous districts of the province of Otago, New Zealand, I was much struck with the similarity, as respects physical geography and geology, between that country and many parts of Scotland. It immediately occurred to me that, in so far as the physical conformation obtained, and the same geological structure existed in many parts of Scotland, there should be a co-equal diffusion of gold as respects at least its area; and I proposed to myself to determine how far this suggestion or belief would be borne out by actual investigation. Since that period I have given all the attention that opportunity permitted to the subject of the diffusion of gold in Scotland, both as regards its area and quantity. I have traversed Scotland in its length and breadth, and visited its principal outlying islands—the Hebrides, Orkney, and Shetland. In 1863 I paid a special visit to the Leadhills district, which, some centuries ago, yielded to systematic working upwards of half a million’s worth of gold, and which, regarded by the test of its then productiveness, is fairly entitled to the appellation of a ‶gold-field.″ In order to compare the Scottish gold and gold rocks with those of other auriferous countries, I made a special examination of the International Exhibition of 1862, and of all the museums accessible to me in Britain, Australia, and New Zealand. I have also studied, so far as appeared to be necessary, the somewhat voluminous literature of gold and gold rocks in