plate, and is made into a thin paste with water; then a small lump of the rock is held in the hand and is rubbed about on the plate with a circular motion, being all the time pressed firmly down. Water must be added from time to time. When a fairly smooth surface has been produced, the specimen should be washed and further ground down upon a square of plate-glass, cut from the "remainders " of a glazier's yard; on this glass a finer emery known as "flour-emery" should be scattered. Plenty of water must be used. The specimen is again washed, and the surface may often be examined successfully in a wet state under the microscope, appearing then as if polished. Or it may be varnished over, which serves the same purpose in producing a good smooth surface. Or it may be fairly polished by rubbing briskly on an old worn carpet, the dust in this helping the operation. The rock gets rather hot to hold, by reason of the rapid friction, and water cannot now be used; but the brisk work of a very few minutes will produce a useful polish. Professional polishing is done with rouge (powdered hæmatite) upon a stretched surface of wash-leather.

Sometimes it is a great advantage to grind a piece of the rock so thin that the light shines through it, in which state it can be examined as a transparent object under the microscope. This is by no means so difficult as at first appears, and any friend accustomed to use the microscope would be willing to assist in the final mounting of the specimen. The simplest way to prepare rock-sections is as follows:

1. Choose a fragment of the rock, as flake-like and as thin as possible, and about an inch across, and grind down one surface with emery.

2. Finish this surface carefully by rubbing, with plenty of water, on a Water-of-Ayr hone, to be obtained of any good tool-shop.

3. Get some ordinary glass slips for mounting microscopic objects, measuring three inches by one inch; dry the rockflake, and cement its smooth surface to one of these with stiff Canada balsam (procurable from a chemist). Heat the slip gently on a piece of metal supported over a lamp, until the balsam slowly gives up the spirit in it, and remains liquid only by reason of the high temperature. This stage can be judged of by dipping the end of a wooden match from time to time into the balsam round the specimen. The balsam

brought away cools quickly in the air, and when it is seen to become brittle on cooling the operation has gone far enough.

4. Then press the specimen firmly down upon the glass slip, to drive out any bubbles under it; remove it from the lamp and let it slowly cool.

5. Now, using the glass as a handle, grind down the remaining rough surface of the rock. In this way the specimen will gradually become possessed of two parallel surfaces; it will become thinner and thinner, until light begins to be visible through it; and it must be finished on the flouremery, and finally on the hone. With care, all parts of it can be made equally thin, and it may then be washed well and allowed to dry.

6. Cover the thin section thus made with Canada balsam, and place on this a thin cover-glass, such as microscopists ordinarily use. Dry the balsam slowly as before, being very careful to avoid overheating and the consequent production of bubbles.

7. The section will now be ready for the microscope. Any balsam that has oozed out upon or round the cover-glass can be lightly cleaned off with a cloth dipped in spirits of wine.

For casual examination, the finished section need not be covered, but may merely be moistened with water, and can thus be examined under the microscope.

A good rock to begin upon is a fairly hard chalk, a substance which grinds down easily and which is yet permeated by the balsam and rendered coherent. Sections of chalk can be prepared entirely on the Water-of-Ayr stone.

So much for indoor considerations and observations. In our walks abroad we must carry two instruments, a hammer and a pocket-lens. The hammer may weigh about a pound, and its head should have a good chisel-like edge on one side and a square steel face on the other. The chisel-edge is best placed perpendicularly to the direction of the handle of the hammer.

A small stone-mason's chisel is always worth carrying, and even a light hammer and a chisel combined will often do what a heavier hammer alone could not effect. Large blocks of stone can be wedged out by steadily driving the chisel into some natural crack.

The best pocket-lens for our purpose is the common "triplet," with three lenses of different power folding up into

one cover.

And now we can at last set off on our travels. We have taken pains to learn something of the alphabet of our subject; and any one of us may hope in time to apply these studies to the actual examination of the earth. In our own immediate surroundings-even in the muddy rivers that run through great cities there is something to be observed, something far more important and interesting than anything which we can learn by the mere reading of books indoors. If I describe in these pages the details of some landscape that is familiar to myself, or bring together for illustration the features of several landscapes, it is with the hope of encouraging each reader to make similar and better observations in his outdoor wanderings for himself. It is well to note down our impressions, making little sketches, however rough, of what we see the form of a boulder, the series of rocks exposed in a quarry, the outline of a hillock or of a mountain-range. Until we put our notes on paper, trying to be as exact as possible, we really do not know how many things we may notice in a short day's ramble; and, when we have written them down, we constantly require to go back again to fill in some gap in our observations. And even then we feel a desire to fit things together, so as to explain them; whereupon we shall find that a single lifetime and our individual wits are quite insufficient for the purpose. We must take counsel of various other people; we must examine their books, and what they have extracted out of previous centuries of books; and all the time we must be on the look-out, for possibly it may be given to one of us to see what no one before has seen exactly in the same way. And then we shall have made a geological discovery.

After all, it matters very little whether the persons who have gone over the ground before us have or have not seen all that we can see. The delight of thus wandering, with our eyes wide open, across the airy moorland or along the shingle of the beach, is one that will grow upon us, and that can never again be taken away from us or lost. We shall be every hour finding out things for ourselves, no longer pent up in museums or laboratories, but among the broad ridges of the world, seeing how the wind, and the streamlet, and the ocean, and the rocks, all work together, with the great sun shining overhead.

us.

CHAPTER II

A MOUNTAIN-HOLLOW

Now let us come out and see what is happening all round Every spring we notice how the trees bud forth again; how the tender coils of the ferns begin to push up through the dead brown leaves that have coloured the hillsides all the winter; how the primroses look out and shine like stars along the green borders of the lane. borders of the lane. In the summer we watch the corn changing, and the fruit reddening on the boughs; in the autumn we notice that the woods are golden, and that the leaves soon begin to fly through the air, as if some caliph of the Arabian Nights were scattering coins in the sunlight. Then, from one year to another, we can see how animals grow up; the little kitten changes, and becomes a quiet old cat that loves to sit by the fireside; the white lambs, which used to run up to us inquisitively in the fields, soon alter into thickbodied and uninteresting sheep. All these things grow, and go on changing; but the fields themselves, the broad slopes where the heather gathers, the barren rocks above, and the long dark ridges of the hills, all these seem to remain, and never to grow, or alter, or decay.

Well, let us set forth on our travels, and keep our eyes well open. Perhaps we may find out that the hills are changing after all.

We must imagine that we wake up on a fine clear morning at the foot of some of our wild mountain-masses in the British Isles-perhaps at the head of Windermere, or in the passes around Snowdon, or in Perthshire, along the great Highland border, or among the purple slopes of Kerry or the barren moors of Donegal. Our little farm-house lodging lies by the high-road up the glen; far away we can see the cart-track winding, now crossing some spur above the stream, now descending to the valley-floor; and on either side of it a few cottages stand dotted about the lower slopes. Above them the steeper moorland rises, grey-green and purple, and

crossed here and there by bands of stones or cut into by rushing little streams.

We must climb to-day steadily up into the hollows of the mountains. We must leave the white cottages far below us; and, as we pass through the last gate in the stone wall, we find ourselves on the open moorland. A few grey blocks of stone lie half buried in the furze and heather; there used to be many more of them, before the farmers gathered them and laid them together to make the walls. Some were so large that they had to break them up with gunpowder; you can still see the marks of the boring-tools on them, where the holes were made in which the blasting-cartridges were placed.

A little above us, a few huge blocks remain untouched; and one or two are as large as a labourer's cottage. If we walk round one of these, we shall very likely find a number of smaller stones wedged up against it, as if they had come tumbling down the slope and had been stopped by their bigger brother. Every now and then we hear faint sounds of water trickling; it is making its way down among the stones that have become quite buried in the grass. If we dig for a little while with a walking-stick, we may be able to see the tiny streamlet flowing; or at any rate we can stoop down and hear it much more clearly. We see that the hillside is partly made of blocks of stone, loosely piled on one another; and the water can find a path between them. It washes along earth and sand as it flows downward, and sometimes in this way it fills up the spaces between the stones, and has then to move away into another course. If you put your hand down into the crevices, you will probably bring up some of the fine sand.

How far down does this assemblage of loose blocks extend into the hill? Well, let us come across to the big stream which here foams down the mountain-side. When we were down below, it looked like a white streak; but, now that we stand by it, we find that it is a fair-sized river. The banks are twenty feet or so in height, and they show us the stuffs of which the ground hereabouts is made. Great blocks of stone stick out on the steep sides, heaped together in a coarse sand. Down where the stream itself is running, we can see the solid rock; and here and there there are fine deep pools, or narrow gorges which look as if they had been