and is intended for more advanced students, the rule will be found pretty rigidly adhered to. Considerable latitude in this respect is allowable in a School Atlas: though even there, it savours more of display than a desire to be useful, when the maps are crowded with names which are nowhere to be met with in the writings of the ancients, except as items in the dry and barren catalogues of Ptolemy or Pliny, or, still later, in the Antonine Itinerary or Peutingerian Tables. Mr Keith Johnston, in his Classical Atlas, has exercised a wise discretion in this respect, and has thus added not a little to the distinctness and beauty of his maps, without any sacrifice of utility. NOTE H.-Page xxxv. In these 'Elements' I have followed out this principle in two ways: 1. A few short and striking quotations, descriptive of the country or of places and things memorable in its history, are attached in the Text to various localities by numerical references at the foot of the page. These it would have been easy to multiply: but it was thought better to limit the selection to such passages as either convey information, or stimulate curiosity by brief and beautiful allusion. It would not be difficult to string together almost any number of verses in which mention is made of the Island of Crete; and yet the combined effect of them all might make less impression than three words in the conclusion of an Ovidian hexameter Jovis incunabula Creten, or the Horatian Sapphic Quae simul centum tetigit potentem d Some pains were also taken in giving accurate references to the original author, in the hope of tempting the student to consult the context, and make himself better acquainted with the poet quoted from :— juvat integros accedere fontes, Atque inde haurire. 2. The geographical portion of the book is closed with a selection of extracts full of interesting local description, which were too long for insertion in the text. Passages of this kind are perpetually occurring in the body of Roman poetry, and the sample here given will serve, among other uses, to shew the importance and necessity of giving a prominent place to geographical instruction in a course of classical education. In making the selection, I had an especial eye to those Latin poets who are scarcely known by more than the name to our educated youth; in order that it might be not merely an Anthologia Geographica, but a fasciculus of specimens taken from Lucretius, Propertius, Lucan, Statius, Silius Italicus, Claudian, &c., and of a kind to vary profitably and agreeably the ordinary school routine. ON THE STRUCTURE OF THE GLOBE AND THE CHANGES IT HAS UNDERGONE. When we remove the loose soil which covers the surface of the earth, we find beneath it rocks assuming various appearances, but which geologists divide into two classes, named with reference to their origin, Igneous and Aqueous, or Igneous and Sedimentary. It is supposed that the materials constituting the mass of the globe had originally a very high temperature, which kept them in a state of fusion, like melted metal, and that the first solid rock consisted of a crystalline crust, formed on the surface of the fluid mass when cooling down, and was of the nature of granite or gneiss. This rock, therefore, was igneous, or the product of fire. The waters of the globe, which first existed in the state of vapour or steam, parting with their heat, condensed into liquids, and collecting in cavities and depressions, formed seas and oceans. The tides and currents of these seas and oceans acting for countless ages on the granitic crust, (which was probably bristled with salient points and ridges, and further roughened by eruptions of fused matter from the molten mass below) tore off portions of it, ground them down to sand or mud, and spread them out on the floor, or bottom of the water, in successive layers, which became consolidated into rock by pressure, or by the infiltration of lime or silica. The rocks so formed are called aqueous, as being the product of water, or sedimentary, because their substance settled down from a state of mechanical suspension in water, as a sediment settles down in a muddy pool, or stratified, because their materials arrange themselves in beds or strata, parallel to each other. Of this description are the sandstones, shales, clay-ironstones, mica and clayslates, impure limestones, &c., seen in the beds of rivers, or on the flanks or crests of mountains; but pure limestones, though stratified, are not strictly speaking sedimentary; they are "chemical precipitates," that is, their constituent parts have not been mechanically suspended in the water but dissolved in it, and have fallen down from it in layers or strata, in consequence of a change in the temperature or condition of the fluid. The oldest sedimentary rocks are thus composed of the "waste" of the primitive crust, or of matter torn off from it and pulverised by agitation in water, hence called "detritus." But the new strata thus formed, were, like the crust on which they rested, shattered by earthquakes or eruptions of igneous matter, and being in their turn exposed to the attacks of tides and currents, furnished additional detritus to aid in the composition of other still newer strata; while the latter were again subjected to the same treatment. In this way, through the whole series of stratified formations, the newer rocks of the sedimentary class have been formed at the expense of the older ones, both sedimentary and igneous. The globe, though its outer crust had cooled down so far as to become solid at a period vastly remote, still retains in its interior a considerable share of its original high temperature. In sinking shafts for mines, and in boring artesian wells for water, the heat is found to increase at the rate generally of one degree Fahr. for each fifty feet of depth. From this it is inferred that at the depth of a mile and a half the rocks will have the heat of boiling water, that lead would melt at the depth of five miles and a half, and silver at the depth of about seventeen miles. The existence of hot springs in so many countries is thus easily accounted for. Water descending through a fissure in the rocks to the depth of a mile and a half, and forced up again to the surface, would, (if it came in a copious stream and rapidly,) have a temperature of 212°. If it came slowly, much of its acquired heat would be lost in ascending. The sedimentary rocks probably have at many parts a thickness of fifteen or twenty miles, and it will be readily conceived, that strata formed of sand or clay, exposed for ages to the high temperature which prevails at such a depth, will undergo some alteration. Accordingly it is found that the oldest stratified rocks shew a |