페이지 이미지

this era, was expended before its close. "There can be no doubt that the infusion of a large amount of this gas into the atmosphere at the present day would be attended by precisely the same circumstances as in the time of the coal epoch. The higher forms of animal life would not have a place on earth. Vegetation would be enormous; and coal strata would be formed from the vast accumulations of woody matter, which would gather in every favorable locality.”


Coal is very widely distributed over the world, although some countries are more highly favored than others. Available coal fields occur in Great Britain; in Spain, France, Belgium and Middle Europe; in India, China and Japan; in the islands of the Indian Archipelago; in Australia and New Zealand; in South America, Chili and Peru; in Greenland, Melville Island and in British America. But nowhere is the coal formation more extensively displayed than in the United States, and nowhere are its beds of greater thickness, more convenient for working, or of more valuable quality.

The eastern half of the continent of North America exhibits five great coal fields, extending from Newfoundland to Arkan. sas: 1. The first, or most eastern, is that of the British Prov. inces, Newfoundland, Nova Scotia, and New Brunswick. Its area is probably about 9,000 square miles, though only one tenth of this surface appears to be underlaid by productive coal seams. 2. The second, or Great Appalachian coal field, extends from Pennsylvania and Ohio to near Tuscaloosa, in the interior of Alabama. It is about 875 miles long, and is estimated to contain 70,000 square miles. 3. A third, and smaller coal field, occupies the center of the State of Michigan; it covers an area of about 15,000 square miles, but is not very productive. 4. A fourth great coal field is situated in the States of Kentucky, Indiana and Illionois. Its area is estimated at 50,000 square miles. 5. The fifth, and most western, occurs in Iowa, Missouri and Arkansas, and occupies an area of about 57,000 square miles. Besides these great deposits, coal is also found in New England, Kansas, Nebraska, and Texas.

The aggregate space underlaid by the coal fields of North America amounts to at least 200,000 square miles, or to more than twenty times the area which includes all the known coal deposits of Europe.- Wells' Geology.


The number of species of animals that now inhabit the globe is about 250,000. The number of fossil species of animals and plants cannot be reliably estimated, but it is safe to say that the number of the different extinct species that have been found in fossil state exceeds many times the number of all the different species now living.

Geologists claim four distinct periods or ages of the earth's history. Beginning at the oldest, they are called or named, First, the Azoic period, or period deficient of the evidence of life ; Second, Paleozoic, or period of ancient life; Third, the Mesozoic, or period of middle life; Fourth, or last period, called Cainozoic. This period includes the Post Tertiary, or recent system of rocks or period of recent life.

A picture of the Azoic period has thus been imagined by Hugh Miller. “During the early part of the Azoic period we may imagine,” he says, “a dark atmosphere of steam and vapor, which, for age after age conceals the face of the sun, and through which the moon or stars never penetrates; oceans of thermal waters, beated in a thousand centers to the boiling point; low, half molten islands, dim through the fog and scarce more fixed than waves themselves, that heave and tremble under the impulsions of the igneous agencies; roaring geysers that ever and anon throw up their intermittent jets of boiling fluid, vapor and thick steam, from these tremulous lands; and in the dim outskirts of the scene, the red gleam of fire shot forth from yawning cracks and deep chasms. Such would be the probable state of things among the times of the earlier gneiss and mica.chist deposits-times buried deep in that chaotic night which must have continued to exist for, may hap, many ages after that beginning of things in which God created the heavens and the earth."

At length, however, as the earth's surface gradually cooled down and the enveloping waters sunk to a lower temperature, let us suppose during the latter times of the mica schist and the earlier times of the clay slate, the steam atmosphere would become less dense and thick, and finally the rays of the sun would struggle through it; at first doubtful and diffused, forming a faint twilight, but gradually strengthening, as the later ages of the slate formation passed away, until at the close of the great primary period day and night-the one still dim and grey, the other wrapped in the pall of darkness-would succeed each other as now, as the earth revolved on its axis.

The number of active volcanoes on our globe are about 275 Humboldt suggests the idea that volcanoes are merely vents. located above some far extended subterranean crack or fissure in the crust of the earth, through which the molten matter of the interior escapes to the surface.

The falls of Niagara are 150 feet in height, and the average amount of water passing over each minute is estimated at 670,000 tons. This water, by its abrading power, has undoubt edly excavated for itself the gorge or channel-seven miles long, 200 feet deep, and 1,200 to 2,000 feet wide-which now intervenes between the falls and Lake Ontario. The minimum time required to wear through this space has been estimated by Sir Charles Lyell, at 35,000 years.- Well': Illustrated Geol.


The stratified rocks of Great Britain have been studied more than any other of the earth, and as the result of these investi. gations it has been found that the extinct mammalia, found in fossiliferous rocks, is more numerous by half than all the species now existing; and of molluscs, the fossil species nine times as numerous as the living species; the fossil fish five times, the reptiles ten times, and the radiate fourteen times.

The geologist finds no trace of that golden age of the world of which the poets delighted to sing, when all creatures lived together in peace, and wars and bloodshed were unknown. Ever since apimal life began on our planet, there existed, in all departments of being, carniverous classes, who could not live but by the death of their neighbors; and who were armed, in consequence, for their destruction, like the butcher with his axe and knife, and the angler with his hook and spear.

In Europe, the caverns or caves that have been discovered, have contained the remains or skeletons of a great many of the different species of animals that now inhabit the earth, and of others tbat are now extinct. For instance, the bones and skeletons of the mammoth are found in great numbers; also of the mastadon, the epoch of the mastadon, in a geolog: ical sense, is very recent. Some think that the mammoths and mastadons did not become entirely extinct in this country until after the advent of man. Sir Charles Lyell is of the opinion that the period of the extinction of the mastadon, although recent, must have been many thousand years ago.



No two particles of matter can occupy the same space at the same time.

All bodies weigh heariest at the earth's surface. A body that weighs 10 pounds at the earth's surface will weigh but 24 pounds 4,000 miles high.

Take two cog-wheels of the same size; let one stand still pat the cogs together and put the other in motion, and when it has made one-half revolution around the standing wheel it will have made a full revolution on its own center, notwithstanding only one-half of the cogs of its own surface has touched the standing wheel.

The atmosphere is the lightest in wet, rainy weather; yet we find people very often who think different. The medium pressure of the atmosphere is about fifteen pounds to the square inch, but this is not always the case. The pressure will vary in the same locality, and sometimes be greater or less. The medium hight that atmospheric pressure will raise water is about 33 feet; but this calculation only holds good at the level of the sea, because as we ascend from the sea level the pressure becomes less; hence, our calculations for raising water by atmospheric pressure must be governed by the pressure that atmosphere has at the hight of the position above the sea level. Illustration: At sea level atmospheric pressure fisteen pounds to the square inch; one mile above sea level, about 121 pounds; two miles above, 10 pounds; three miles, 74 pounds; consequently, on an elevation three miles high, water cannot be raised but about 164 feet by the weight of the air.

The top or upper part of a wagon wheel passes through a greater amount of space in a given time when running than the bottom; or, in other words, runs the fastest.

The piston rod of a steam engine makes two complete stops at every revolution of the crank attached to the end of the pitman,

HORSE POWER.—The average power of a horse is sufficient to raise a weight of about 23,000 pounds one foot per minute, but when calculating the horse power of a steam engine it is estitmated at 33,000 pounds. It then follows that a ten horse powers team engine is, in fact, about equal to fourteen average horses.

POWER OF STEAM.-One cabic foot of water converted into steam will raise the enormous weight of three and a half million pounds one foot, or seven hundred pounds one mile high.

All bodies or particles of matter fall to the eath by the attraction of gravity, and their speed is in proportion to their density; but take away the resisting force of the atmosphere, then a cork or feather will fall as fast as a bullet.

Resultant motion may be illustrated by holding a ball or weight in your hand and dropping it from the top of your head while running, you will find that you cannot run fast enough to overtake the ball before it strikes the ground.

A ball may be shot from a cannon from the top of a tower on a horizontal plain, and another dropped from the mouth of the cannon at the same time, and they will both strike the earth at the same time, provided the surface be horizontal with the cannon.

Lever power is almost indispensable, or in other words, without it we could scarcely do anything; yet to take in consideration distance and speed, there is not a particle of power gained by a lever. Illustration: Suppose a lever 20 feet long, the fulcrum 2 feet from one end of the lever, 10 pounds on the long end of the lever is equal to 100 pounds on the short end; but to raise the 100 pounds one foot the ten pounds passes through 10 feet of space, consequently it travels ten times as fast as the 100 pounds, so all that is gained in power is lost in speed and distance; because if both ends of the lever was of the same length while one end of the lever was passing through ten feet of space the other end would pass through the same ten feet; and ten pounds would raise ten pounds ten feet high, or ten times as high as the ten pounds on the long end of the lever would raise the 100 pounds on the short end,

« 이전계속 »