page 459 note * In Jameson's, “Mineralogical Travels,” vol. ii. p. 33Google Scholar, we see that this pale variety was considered corundum by the Hon. Mr Greville. Jameson considered the sphenes to be garnets.

page 460 note * In the Chemical News, Feb. 17, 1871, Mr E. C. C. Stanford gives the following analysis of the dark green crystals imbedded in the pink matrix of the Tiree marble:—

which analysis is said to correspond with some already published of aluminous hornblende, and to prove these crystals to be hornblende.

It has first to be remarked that Jameson, Macculloch, and all mineralogists who have examined these crystals recognise them as, without doubt, augite. Second, that this analysis of the same substance as that noted above, presents an extraordinarily discordant result therewith. And lastly, that in no particular whatever, except in the quantity of lime, does it agree with any one of the 52 analyses of aluminous hornblendes published by Dana. In hornblende, alumina, when present, replaces silica; but, without even deducting the 22 per cent, of alumina, the silica here is in excessive amount.

page 467 note * I have in the figure, alongside of the rough crystals of this augite, placed for comparison a figure of the equally rough cleavage crystals of the Paulite (true hypersthene), with which they are sometimes associated; in these the m angle is slightly more accute; b is the face of facile cleavage, its lustre being bronzy and somewhat purple. There is, at right angles to this, more a fracture than a cleavage, a, the colour of which is black.

page 469 note * Aisgobhall of Jameson.

page 470 note * Dudgeon and the Author found on the banks of a stream which flows from the north side of Glamich loose masses of a volcanic breccia—somewhat similar to that of Rum—but which, among fragments of schists and conglomerates, contained many of blue-grey “indurated” limestone.

page 476 note * My friend, who most generously made over to me the cherished gleanings of his many and even midnight wanderings among the Coolins,—repelling my slanders concerning the beautiful product of the hills he loved so well,—put the most bronzy specimens remaining into the hands of a lapidary to be cut into brooches. He was horrified when the stone was returned to him in fragments, with the explanation that they were “all rotted.”

page 477 note * While correcting the proofs of this paper, I have, for the first time, had the pleasure of perusing Professor Judd's classical research on the rocks of Mull. In this I find that he, throughout, unhesitatingly calls the Eum rock gabbro. Now—whatever rock Yon Buch originally applied the name to,— the term gabbro is now, I believe, universally attached to a combination of labradorite with diallage. I went round the whole shore of Rum, traversed the island in three directions, ascended seven of its highest hills, skirted the flanks of these, and yet, not only did I never see a particle of diallage in the island, but I never saw a bit of the augite which even tended in features to that modification. I need hardly, therefore, say that I saw no gabbro. It may be held that this is mere fighting for a word; but it is not so, it is fighting for precision in language. If gabbro is to be extended or loosened in its application so as to include an ordinary augitic rock, I have nothing to say, further than to show that it would be most unadvisable to do so. But till a consensus of geologists resolves to do so, it must tend to endless confusion, that the author of so masterly a research as that referred to,—speaking almost ex cathedra,—applies the term to a rock so absolutely different in appearance as the present is from any typical gabbro. I am the more sensitive as regards writing by the booh in the present case, because, so far as my experience goes, the gabbros of Scotland—that is, the rocks carrying thin, foliated lustrous augite, and they are very typical—are all metamorphic. Be this as it may, it is not advisable that the name to be adopted for a class of rocks should be one which in the past has designated a variety, the marked feature of which is, that it contains a peculiar modification of that substance which is the chief constituent of all the members of that class. We might, it is true, designate that variety by the term diallagite; but let us understand each other, as a necessary preliminary to our entertaining the hope that others will understand us.

page 490 note * Orthoclase requires nearly a white heat.

page 492 note * Specially at the Bay of Durn, north of the Battery, and the first bed to the west thereof.

page 500 note * Streng considers Schiller spar as altered bronzite (enstatite); Descloizeaux, however, finds that it has a negative bisectrix, which makes it altered diaclasite. In the lustrous portion there is really no apparent alteration; and the hardness, gravity, and colour are all nearer diaclasite.

page 507 note See Greg and Lettsom

page 514 note * “Trans. Highland Soc.” vol. xiv.

page 517 note * Would it not, then, be a “violation of natural union” to “attempt a separation” of the ten beds which, on the west shore of the Bay of Durn, alternate with, without once intersecting, each other?

page 525 note * The occurrence of this variety is another proof of the undesirableness of naming minerals from a single external character. There are numerous bronzy minerals in Scotland; I do not know that true bronzite occurs. The name is nearly as unsatisfactory as is that of chlorite.

page 529 note * Lately corrupted to Ferry Port on Craig.

page 534 note * It may appear strange to speak of a slicltenside lustre, but, except in the case of metallic minerals, the lustre of all slickenside surfaces is mueh the same, and quite peculiar;—it may be said to be the lustre of reflected light.

page 548 note * Water in certain situations appears to polish—as in the rock-runnels of streams, the pot-holes of rivers, the back-tow crevasses of the seashore, and some undercut beach rocks or cliffs. In all these cases, sand or stones, held in the grasp of the water, have done the work, which was of the nature of grinding or chiselling. Most interesting illustrations of simple wave-action, and of this compound pummelling and rasping process, are to be seen at low water beneath the Kincraig near Elie.

page 549 note * Jameson says that he found enough of this in the island to load an Indiaman,—and this is the spot where it occurs.

page 551 note * Nicol's, “Manual of Mineralogy’ p. 208Google Scholar. An epitomy of the views of Gustav Rose.

page 552 note * The felspar of the Morven syenite I have not yet determined. There is also a peculiar rock found north of Shinness in which the felspar may be orthoclase.

page 553 note * “Mineralogy,” p. 240.

page 553 note † Ibid. p. 343.

page 554 note * The belt on the Deskory may be the same.