2. What do you call the Heavens?

A. Those regions of space, which in common discourse we call the sky, or the air, which we perceive all around us above the atmosphere, in which are situated all the shining bodies, the sun, moon, planets, and stars.

GEOLOGY.

2. What is the science called geology?

A. It has for its object the structure and principles of the formation of the globe we inhabit; and it embraces investigations and conjectures on its origin and internal composition; and the study of the particular composition of its various parts. There are two classes of philosophers, who hold different opinions on its origin, and they argue from the appearances which the earth presents, its solid masses, and its waters; these two classes are designated by their systems, which are the Plutonians, or those of whose theory fire is the principle; and the Neptunians, the principle of whose theory is water.

Who were most eminent in these classes? A. Among the first were Des Cartes, Leibnitz, Buffon, who supposed the earth to be of the same nature as the sun; and Whiston, who supposed the earth to have been a comet, composed of a fragment ejected from the sun, and after a time cooled down.

The Neptunians, were Burnet, Pallas, Hutton, Woodward, De Luc, Kirwan, and La Metherie, assert a watry origin. The first class suppose the earth to contain a mass of fire in the centre; whence volcanoes are accounted for. But the second class believe the earth to be solid, and account for volcanoes upon chemical principles; it being known that iron filings and sul

phur placed under ground, will take fire and explode....so volcanoes may arise from iron and sulphur brought together by alluvion.

Is this the whole science of geology?

A. This science treats of the encrease and decrease of the land and waters, and the composition of mountains, and the general surface of the earth, which is described as composed of classes of rocks which are called primitive and secondary, formed principally of three ingredients, variously intermixed, that is silex, alumina, and magnesia....constituting the following: 1, granite ; 2, gneiss; 3, mica slate; 4, clay state; 5, primitive limestone; 6, primitive trap; 7, serpentine; 8, porphyry; 9, sienites; 10, topaz rock; 11, quartz rock; 12, primitive flinty slate; 13, primitive gypsum; 14, white stone.

But there is another classification of rocks into five kinds. 1, primitive, composing all that we have above noted; and four others comprehending all the secondary class; 2, rocks of transition; 3, stratified or secondary rocks, by alluvial deposition; 5, volcanic rocks.

The secondary class, supposed to be the result of decomposition and solution, by heat, air, and water, are: 1, old red sand stone; 2, first old floetz or lime stone; 3, first or oldest floetz_gypsum; 4, second or variegated sand stone; 5, second floetz gypsum; 6, second floetz or shell lime stone; 7, third floetz or sand stone; 8, rock salt formation; 9, chalk formation; 10, floetz trap formation; 11, independent coal formation; 12, newest floetz trap formation.

All the surface of the earth is composed of one or more of these materials; the latter are called alluvial, and may be divided into two classes....1, deposits formed in moun

tainous countries, and found in vallies composed of solid masses of rock, gravel, sand, loam, fragments of ores, and sometimes precious gems. 2, the soil of low flat countries, as peat, sand, loams, bog iron-ore, breceia, tufa, stalactite, &c. All these and other natural parts of the globe, are particularly investigated by the aid of two other sciences....mineralogy, which classes all the hard substances, and discriminates their characters; chemistry, which by decomposing them, exhibits their elementary principles.

OF THE ATMOSPHERE.

Q. What is the atmosphere?

A. A transparent, invisible, and impalpableliquid matter, composed of air and other matter encompassing on all parts the terrestrial globe, and at times resembling vapor or smoke. Its use is to furnish winds and rain, and serve for the common purpose of breathing; it is also the cause of the morning and evening twilight.

2. What is the extent of the atmosphere ?

A. It is extremely difficult to determine its exact height. Were it as dense as on the surface of the earth, it would not exceed six miles. In general, however, it is supposed to be about twenty-seven or twenty eight miles; and its greatest altitude cannot be more than forty-five or fifty miles; for the more distant from the earth it is, the thinner and lighter it becomes, and a smaller quantity of it occupies a larger space. We may justly say the atmosphere serves as a veil or covering to the earth.

2. Is the atmosphere heavy ?

A. The atmospheric air, by experiments, has been found to be 914 times lighter than water.

It is this, even near the surface of the earth, where it is the heaviest: in the higher regions it is still lighter. For the air is composed of a high, middle, and lower region.

The air of the higher region is more subtle and more cold than that of the middle; and that of the middle is finer than the lower.

The weight of a column of air, reaching from the surface of the earth to the top of the atmosphere, is equal to that of a column of water, of the same diameter, 33 feet high; for so high, and no higher will water rise in a pump, by the pressure of the external air, after the air within the pump has been extracted by the piston or sucker. Now the weight of a square column of water, one foot thick, and 33 feet high, is 2160 pounds; so that a man of a middling size, the surface of whose body is 14 square feet, sustains a pressure of air of 30240 pounds, when the air is of a moderate gravity; a pressure that would be insupportable, and even fatal to him, were it not that it is equal on every part, and counterbalanced by the spring of the air within him, which is diffused through the whole body, and re-acts with an equal force against the outward pressure. Hence it is that a column of mercury in the barometer, from the same principle, does not rise higher on a medium than 29 inches and a half, its specific gravity to that of water being nearly as 14 to 1.

OF METEOROLOGY.

2. What is a meteor?

A. A meteor generally is any matter engendered in the air which surrounds us, and which puts on the appearance of a fire or flame, so as

B

to become visible to our sight. hends numerous objects;

It compreas clouds, aurora

borealis, what is usually called falling stars, and the rainbow is a meteor.

2. How are they treated of?

A. Meteorology is reduced to a science, and 'into three classes or kinds : 1, igneous or fiery ; 2, aerial or volatile; 3, aqueous or watery.

2. What is generally supposed to be the cause of the common evening meteor?

A. Some recent publications assert that from a meteor of this kind, a matter has been caught having the properties of lime.

2. It would then appear that a meteor is something collected in the air which is inflammable.

A. Certainly modern chemistry has shewn that even various kinds of air brought into contact take fire and explode.

2. Are there not other meteors?

A. Luminous appearances are often seen in the heavens; balls of fire of great apparent bulk have been seen passing rapidly across the horizon; the aurora borealis, or northern light, is a very splendid meteor; very heavy stones have descended from the atmosphere, the origin of which cannot be accounted for; some have supposed these stones to have been cast off from some one of the planets or from some comet.

2. Will you describe what relates to the rest of the universe, the planets, comets, and so forth?

A. In subsequent classes the most curious objects of nature shall be described; but it is necessary first to enquire concerning matters that will enable us better to comprehend them.