neath; and, to imitate as far as possible the condition of the geyser, the tube is encircled by a second fire, F, at a height of two feet from the bottom. Doubtless the high temperature of the water, at the corresponding part of the geyser tube, is due to a local action of the heated rocks. The tube is filled with water, which gradually becomes heated to the

boiling temperature; and regularly, every five minutes afterwards, the liquid is ejected into the atmosphere.

There is another famous spring in Iceland called the Strokkur, which is usually forced to explode by stopping its mouth with clods. We can imitate the action of this spring by stopping the mouth of our tube A B—not too tightly be it observed with a cork. The

heating progresses. The steam finally attains sufficient tension to eject the cork, and the water, suddenly relieved from the pressure, bursts forth into the atmosphere. The ceiling of this room is nearly thirty feet from the floor, but the eruption has reached the ceiling, from which the water now drips plentifully. In fig. [3] is given a section of the Strokkur.

FIG. 3.

By stopping our model geyser tube with corks, through which glass tubes of various lengths and diameters pass, the action of many of the other

eruptive springs of Iceland may be accurately imitated. We can readily, for example, produce an intermittent action; discharges of water and impetuous steam-gushes following each other in quick succession, the water being squirted in jets fifteen or twenty feet high. These experiments completely verify the theory of Bunsen, and we are relieved from the necessity of imagining underground caverns and syphons, filled with water and steam, which were formerly regarded as necessary to the production of these wonderful phenomena.

A moment's reflection will suggest to you that there must be a limit to the operations of the geyser. When the tube has reached such an altitude that the water in the depths below, owing to the increased pressure, cannot attain its boiling point, the eruptions of necessity cease. The spring, however, continues to deposit its silica, and often forms a Laug, or cistern. Some of those in Iceland are forty feet deep, and their beauty, according to Bunsen, is indescribable. Over the surface curls a light vapour, the water is of the purest azure, and tints with its own hue the fantastic incrustations on the cistern walls; while, at the bottom, is often seen the mouth of the once mighty geyser. There are in Iceland traces of vast, but now extinct, geyser operations. Mounds are observed, whose shafts are filled with rubbish, the water having forced a passage underneath and retired to other scenes of action. We have, in fact, the geyser in its youth, manhood, old age, and death here presented to us. In its youth,

as a simple thermal spring; in its manhood, as the eruptive column; in its old age, as the tranquil Laug; while its death is recorded by the ruined shaft and forsaken mounds, which testify the fact of its once active existence.

GEORGE GROTE: THE PHYSICAL GEOGRAPHY

OF GREECE

From "A History of Greece," London, 1869, vol. ii. pp. 216-230.

[The footnotes are omitted.]

I have chosen this specimen of explanatory description partly to show how description and exposition, in the ordinary use of the terms, run into each other, partly to emphasize the limitations and peculiar province of explanation by means of words, partly for the sake of the skilfully emphasized connectives.

The first point needs little illustration: a glance at the third paragraph will show that it may be called either exposition or description. The second point, the limitations of explanation by words, is made clear in the first sentence, in which Grote suggests that to understand the careful geographical description which immediately precedes this selection you must read with a map before you: as a matter of fact, the geographical description is unintelligible without the map. It is only when Grote turns from the pure topography to the consequences of it on the life of the people that words begin to serve his purpose better than the map. In the case of pure relations of time and space words are only a halting and clumsy means of explanation; for such matter use diagrams and symbols. On the other hand, for the more complex relations of concrete things in actual life, words which can name these concrete realities with all their connotations are your chief and your best dependence. The third point, the skill with which Grote uses his connectives, I have discussed in the Introduction, p. 45.

By this brief sketch, which the reader will naturally compare with one of the recent maps of the country, it will be seen that Greece proper is among

the most mountainous territories in Europe. For although it is convenient, in giving a systematic view of the face of the country, to group the multiplicity of mountains into certain chains or ranges, founded upon approximative uniformity of direction; yet in point of fact there are so many ramifications and dispersed peaks so vast a number of hills and crags of different magnitude and elevation that a comparatively small proportion of the surface is left for level ground. Not only few continuous plains, but even few continuous valleys, exist throughout all Greece proper. The largest spaces of level ground are seen in Thessaly, in Etolia, in the western portion of Peloponnesus, and in Boeotia; but irregular mountains, valleys, frequent but isolated, land-locked basins and declivities, which often occur but seldom last long, form the character of the country.

Geological fea

tures.

The islands of the Cyclades, Euboea, Attica, and Laconia, consist for the most part of micaceous schist, combined with and often covered by crystalline granular limestone. The centre and west of Peloponnesus, as well as the country north of the Corinthian Gulf from the Gulf of Ambrakia to the strait of Euboea, present a calcareous formation, varying in different localities as to colour, consistency, and hardness, but generally belonging or approximating to the chalk: it is often very compact, but is distinguished in a marked manner from the crystalline limestone above-mentioned. The two loftiest summits in Greece (both however lower than Olympus, estimated at 9700 feet) exhibit