DIVISION OF THE WATERS. 29 LETTER III. Bless the Lord, O my soul. O Lord my God, thou art very great; thou art clothed with honour and majesty. Who coverest thyself with light as with a garment: who stretchest out the Heavens like a curtain; who layeth the beams of His chambers in the waters: who maketh the clouds His chariot: who walketh upon the wings of the wind.-Psalm civ. 1-3. MY DEAR CHILDREN, IN each of the days of Creation, as I before remarked, there was a wonderful provision made for those which followed. This is especially the case in the second day, when the Firmament, or what is better known to us as the Atmosphere, came into existence. The language which records its Creation is very full:-"And God said, Let there be a firmament in the midst of the waters, and let it divide the waters from the waters. And God made the firmament, and divided the waters which were under the firmament from the waters which were above the firmament: and it was so. And God called the firmament Heaven. And the evening and the morning were the second day." Thus did the Lord by this one act of creative power bring into being that by which all life, whether vegetable or animal, was destined to be sustained. A vast body of water was also gathered up into the atmosphere, and suspended there in clouds, which became as the garment thereof. (Job xxxviii. 9.) Thus the waters were divided from the waters; and the means provided by which the earth might be continually refreshed by the early and the latter rain: for the clouds became, from this day, God's appointed reservoir of the rain and snows, which in due season should come and water the earth, to make it bring forth and bud, giving seed to the sower and bread to the eater. (Isa. lv.) But the subject of the atmosphere is so full of interest, both as to its formation and various properties, that we must not hastily pass away from it. And here I must of necessity use some scientific terms; but though I know such hard names at first sight may seem difficult to remember, yet be assured that the language of science, if not the most beautiful, is the most expressive; for every word carries within itself its own signification; whilst, therefore, dear children, I will seek to avoid an unnecessary use of these terms, I have little doubt but we shall soon agree that they are even easier to retain than words in common use. First, then, let me explain to you the formation of the atmosphere, or the air, with which we are surrounded. Naturalists —that is, men of science who have made these subjects their especial study-have ascertained that the air is composed of two principal gases, or elastic fluids, which have been named by them Oxygen and Nitrogen. The first is emphatically the sustainer of life, animal and vegetable; the second has no such power, and so has been also called azote, that is, without life: but as the oxygen would be too active alone, it is diluted with nitrogen, as water dilutes wine. The relative proportions are,-twenty parts oxygen, eighty nitrogen. In addition to these, there is also a small portion of carbonic acid gas, and some hydrogen, but only in the proportion of one part to ninety-nine. The height of the atmosphere, it is calculated,. does not exceed fifty miles,* expanding all the while as it * It is a singular thing to say, that we can weigh that which we cannot see; and yet this is strictly true of the atmosphere. We little think how it is pressing upon us on every side; for it is calculated, that on the body of a fullgrown man its pressure is equal to thirty thousand pounds; but then, as it presses equally on every side, and as also we have an equal resistance within, we not only do not feel any inconvenience from it, but positive blessing. But as a proof of the pressure of the atmosphere, supposing you exhausted the air from a thin vessel, the outward pressure of the atmosphere would crush it to pieces. But the principle of expansion of the atmosphere is as wonderful as that of its condensation; for it is calculated, that at the height of five hundred miles a cubic inch of rarefied air would fill a sphere equal in diameter to the orbit of Saturn. The proof of the power of expansion is very simple. Suppose you put into an air-tight vessel a bladder, with its mouth tied, out of which you have expelled as much air as possible, and then exhaust the air |