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218 may help his understanding of that which is to come. If not provided with maps, etc., we had better go at once to London and provide ourselves at Stanford's. While in London we must not fail to visit the Museum of Practical Geology in Jermyn Street, which issues a number of catalogues of permanent value (33), and a geological guide to London, and contains models and collections of all kinds. Every one will admire the polished marbles, granites, and serpentines. If we have a Saturday free, an excursion of the Geologists' Association may attract us. At any rate, we shall notice that London lies in a geological basin, and, if our drinking-water is from some deep artesian well, we may thank our stars that London has such a favored situation as not to be entirely dependent for water-supply upon the filthy Thames. Let us go north. There are three main lines of tourist travel. The most westerly passes by the lake district of Westmoreland and Cumberland. It is curious to note how uniformly that combination of mountain and lake which is most attractive for summer resort occurs where a region of metamorphic rocks has been subjected to glacial action. Lake Superior and Windermere, Maine and Switzerland, all answer to this description. We dare not stop to discuss the reasons. (See 4, chapter xxvii; 10, p. 516.) We shall see the same sort of thing in the Trossachs and Switzerland. If you want to do any detailed work in the region, start in from Keswick, where a museum contains local collections and models.

Scotch surface geology is of the same glaciated type so familiar in America, and those who wish to study the parallel roads of Lochaber, or the Tertiary gabbros of Judd, must turn to the Scotch survey for guidance (3, 5, 13). For us an excursion or two about Edinburgh must suffice. The collections of the Museum of Science and Art are fine, and we can climb the volcanic crags of Castle Hill, Calton Hill, or Arthur's Seat, and wonder what the landscape was like when hot lava rolled down Salisbury crags. At Newhaven, near by, on the shore of the Firth of Forth, the clay ironstone is exposed, and, breaking open the oblong pebbles, you may find a fish, but more likely a coprolite or septarium. If you wish to see more of the Carboniferous and the coal and iron industry, you have only to run down to Gilmerton, near which are numerous coal-mines, and great piles of iron-ore a-roasting. Ganoid scales and teeth are not rare, and are collected by some workmen. The name of one was Joseph Blair, of Loamhead.

On our way south again we shall probably pass through the Peak of Derbyshire and behold the scenery of the subcarboniferous, the great mountain limestone in its most beautiful development, its dewy dells, its steep yet rounded bluffs, and its