LESSON I.

CHEMICAL COMPOSITION OF WATER.

ATER, which is necessary to the support of animal and vegetable life, is very widely diffused and copiously supplied. It is found in three forms: vaporous in the atmosphere, solid in ice and snow, and liquid in rivers and seas. It belongs to this part of physical geography to treat of it in the last condition.

198. Water is composed of two gases, oxygen and hydrogen, in the proportion of eight parts of the former to one of the latter. It is one of the most marvelous facts in the natural world, that, though hydrogen is highly inflammable, and oxygen is a supporter of combustion, both, combined in water, form an element destructive to fire. By processes well known to the chemist, water may be readily resolved into its constituent elements.

199. Pure water is destitute of color, taste, and smell. It seldom occurs, however, in this state, but contains various ingredients, derived either from the atmosphere or from the earth. Rain-water is the purest that can be obtained except by distillation. Spring and well water contain many earthy substances in solution. The brackish taste of wells in countries abounding in limestone is owing to the presence of that substance. River-water has its character determined by the soil and vegetation of the country through which it flows.

200. The waters of the globe are divided into the fresh and salt. The fresh waters include those of all streams and rivers, nearly all the springs, and the greater number of lakes and marshes. They are so called because they contain no amount of saline matter unfitting them for use. It is supposed that the lakes of North America contain more than half the amount of fresh water on the face of the globe.

201. Salt water is that which fills the vast basins of the ocean, besides numerous lakes and springs: it forms by far the largest portion of the liquid element. The proportion of saline matter which the ocean contains is about 3 per cent. The principal salts contained in sea-water are common salt (chloride of sodium), Glauber's salt (sulphate of soda), Epsom salt (sulphate of magnesia), chloride of magnesium, sulphate and car bonate of lime,-common salt being the most considerable in amount.

Supposing the sea to have a mean depth of 1,000

Questions.-197 What is said of water? In what three forms is it found? 198. Of what is water composed? What marvelous fact is stated respecting water? 199. What is the character of pure water? Does it commonly occur in this state? What kind of water is the purest? What do spring and well water contain? To what is the brackish taste of wells in limestone countries owing? By what is the character of river-water determined? 200. How are the waters of the globe divided? What do the fresh waters include? Why are they so called? What is said of the lakes of North America?

feet, it has been calculated that the amount of common salt it would contain would be equal in extent to five times the mass of the Alps, or one third less than that of the Himalaya Mountains.

202. Oceanic waters vary in the quantity of saline matter they contain in different places. From observations made, it is found that the degree of saltness diminishes toward the poles, and also near the shores. This is owing to the melting of snow and ice, and to the volumes of fresh water poured in by the rivers. It is also ascertained that the waters of the southern hemisphere contain more salt than those of the northern, while the Atlantic is in excess of the Pacific.

203. Salt water has an extensive distribution in lakes and springs, and these are remarkable for the great proportion of saline matter they contain. The western part of Asia and the southern part of Russia constitute the great salt-water lake region of the globe. The Caspian Sea, lakes Aral, Urumiah, Elton, and the Dead Sea occur in this district. Some of these waters are so salt as to irritate the skin. Fish can not

DEAD SEA.

live in them, and if a bird dips in their surface, its wings, on drying, are incrusted with salt. The waters of the Dead Sea contain about 25 per cent. of saline matter. Lake Elton, in the steppe east of the Volga, is more strongly impregnated with saline ingredients than any other known example, containing 29 per cent.

204. Water is one of the most widely diffused bodies of nature. We have seen (12) that the surface of the earth is estimated to contain 196,500,000 square miles, and that the dry land occupies only about 51,000,000— leaving 145,500,000 square miles to be occupied by the fluid

element.

205. The benevolence of the Deity is manifest in the wide. diffusion of this element over the globe. As a nutritive or alimentary substance, it is indispensable to both the animal and the vegetable world. It serves invaluable purposes in the arts and manufactures; in its application as a motive power; and, when occurring in large bodies, in the form of rivers, lakes, and seas, as a medium for the more rapid or more commodious transport of goods or persons from one locality to another. To the vast reservoir of the ocean are we indebted for the clouds which carry the moisture from the sea

.

Questions.-201. What is said of salt water? What proportion of saline ingredients does it contain? What are the principal salts in sea-water? Which is the most considerable in amount" Illustrate. 202. How do oceanic waters vary? Where is the saltness of the ocean found to diminish? Cause? Between what other regions is the saltness unequal? 203. What is raid of salt lakes and springs? Where is the great salt-water lake region? Examples. 204. Diffusion of water? Extent of the liquid element?

205. Mention some of the uses of water

to Him who so created and distributed it. wants and necessities, we can not but be filled with gratitude itants of the earth in the conditions best adapted to their water, and notice how universally it is supplied to the inhabing rain; indeed, when we study the uses and properties of and let it down upon the parched and thirsty earth in refresh

attention before proceeding with the following lesson NOTE.-The questions on the neighboring map should receive

QUESTIONS ON THE MAP.

OCEANS, SEAS, ETC.

What two great oceans are separated from each other merely
by a succession of islands? What two are connected solely
by a narrow strait? With what part of the Arctic Ocean does
nearly half the breadth of the North Atlantic unite?

What ocean is most thickly studded with islands? What is
the vast island-region of the Pacific called? Ans. Oceanica. Does
it extend nearest to America or Asia? What part of the Pacific
presents the broadest expanse of ocean uninterrupted with islands
to be found on the globe? Near what part of the same has the
Antarctic Ocean been explored farthest south? [See lower right-
hand corner of the map.]

Which of the oceans is bordered by the greatest number of
seas separated from it chiefly by islands? Name some of these
What ocean has the most seas, gulfs, and bays, commu-
nicating with it, which extend far into the continents, or are
nearly land-locked? Name some of these seas, etc.

seas.

SYSTEMS OF DRAINAGE.

NOTE. The student will recollect that in the questions on the preceding
map, attention was called to the fact that the short and abrupt slopes of the
continents, in consequence of the situation of the great mountain-chains,
are toward the Pacific and Indian oceans; the long slopes, in the opposite
directions. Hence the system of drainage is as it now appears.

On which continent has the Pacific basin or region of drainage
its greatest extent? On which, the Atlantic basin? Name the
great rivers belonging to the Pacific basin in Asia. To the
Atlantic basin in America. To the same in Europe and Africa.
Does the basin of the Arctic Ocean extend widely on the con-
tinents? [It will be remembered that, as the neighboring map is drawn
on Mercator's projection, the northern and southern regions are much en-
larged beyond their true relative size. This will be perceived on comparing
it with a globe or map of the hemispheres.] On which has it the
greater area? Name the great rivers which it includes on the
Eastern Continent. On the Western.

What two grand divisions together contain an immense region
of inland drainage? What great salt lakes or seas receive most
of the waters of this region? Which are the chief tributaries of
the Caspian?

OCEAN CURRENTS.

heated waters of the Gulf of Mexico, sweeps across the North
Atlantic? Into what ocean is a part of the waters of the Gulf
Stream discharged? What is the course of the other part?
What extensive bank or collection of floating sea-weed lies be-
tween the Equatorial Current and the southern branch of the
Gulf Stream? By what other name is this sea-weed region often
called? Ans. Sargasso Sea.

What current from the Arctic regions flows east of Greenland?
What one from Baffin and Hudson bays unites with it, and flows
between the Gulf Stream and the American coast?

What current originating in the southeastern flow of the Gulf
Stream runs along the northwest coast of Africa?
What one
from the Gulf of Guinea flows south to the Antarctic Ocean?
What branches from the Equatorial Current of the Indian Ocean
unite with this?

What branch from the Equatorial Current of the Pacific, near
the coast of Asia, has a similar course to that of the Gulf Stream?
By what name is this current designated in the northeastern
part of the Pacific?

What great current on the west coast of South America is
tributary to the Equatorial Current? By what general name is
the northeastward flow of waters from various parts of the An-
tarctic Ocean termed ? What is that branch called which sweeps

past Cape Horn?

LESSON II.

MINERAL SPRINGS.

unfitting them for a beverage, or for culinary purposes. render them hard, and impart to them a disagreeable taste, holding in solution a considerable portion of neutral salts, which guished by their repulsive smell; and (4) saline, or springs hydrogen, or sulphuret of lime, etc., and which are distinof iron; (3) sulphurous, or springs containing either sulphureted springs holding in solution either the carbonate or the sulphate (1) acidulous, such as contain carbonic acid; (2) chalybeate, or 206. MINERAL waters may be divided into four classes:

canoes.

is

tain? Springs at Salina and Syracuse? On the Great and Little Kanawha? At Droitwich ? springs? Examples. Where numerous? 210. Saline springs? Quantity of salt they con. hisar? A river in South America? 208. Chalybeate springs? Examples. 209. Sulphurous Saline? 207. Appearance of acidulous waters? Carbonic acid gas? Spring near KızQuestions.-206. Mineral waters, how divided? Acidulous? Chalybeate? Sulphurous?

about one bushel of pure salt. at these springs over 3 millions of bushels of salt. occur also on the Great and Little Kanawha rivers, in Virginia, inexhaustible supply of water, yielding to every forty gallons of this class. The principal spring at Salina village affords an lina and Syracuse, in the State of New York, are noted examples they yield one fourth of their weight in salt. The springs at Saquantity of chloride of sodium in some of these springs, that diffused throughout the surface of the earth. So great is the of chloride of sodium, or common salt, and are very generally 210. Saline springs contain a greater or less proportion In 1850 there were manufactured Salt springs

phurous springs are very numerous in volcanic countries. those of Ilarrowgate, and St. Bernard's Well, England. Suldrogen, cr of sulphate of lime. Of the springs of this class are sulphur, which usually occurs in the form of sulphureted hy209. Sulphurous springs are so named because they contain

Brighton, England, belong to this class. ing other substances. The springs at Tonbridge Weils and the term is, however, occasionally applied to springs contain208. Chalybeate springs are such as contain oxide of iron;

with this gas, that the Spaniards call it Vinagré (vinegar). in a volcanic mountain, has its waters so greatly impregnated river in South America, a tributary of the Magdalena, which rises rises very cold, but bubbles up like a boiling caldron. A small of this description occurs in Asia Minor, near Kiz-hisar, which vessel into another. A remarkable spring containing water Acidulated waters sparkle when poured from one but more particularly in the vicinity of active or extinct volthey owe to the presence of carbonic acid gas. This gas very plentifully disengaged from springs in almost all countries, 207. Acidulous waters present a sparkling appearance which

which yield about a bushel of salt from every 60 or 70 gallons of brine. At Droitwich, England, is a celebrated brine spring which produces annually about 700,000 bushels of salt.

211. Besides the springs above described, there are others whose waters are impregnated with various mineral substances which impart to them medicinal properties, as those at CheltenLam, England, at Carlsbad, Germany, and at other places.

212. The mineral springs of the United States are numerous and valuable: they are extensively distributed, but those of New York and Virginia are the most celebrated. Among those in the State of New York are, the chalybeate springs of Saratoga, the sulphur springs of Sharon, Avon,, and Clifton, and the petrifying springs of Madison and Saratoga counties. Saratoga is remarkable for the number and variety of its springs, the waters of which are celebrated for their medicinal properties.

213. Among the most celebrated of the springs at Saratoga, are Congress Spring, High Rock Spring, Hamilton Spring, Putnam's Spring, Iodine Spring, Pavilion Spring, and Empire Spring, not any two of which are alike in the composition of their waters. Congress Spring is the general favorite of visitors; it is highly acidulous. Hamilton, Putnam, and Pavilion springs are chalybeate. Iodine Spring contains but a small proportion of iron, and may be drank by a certain class of invalids, with whom iron proves a decided injury.

214. Virginia abounds with mineral springs, but the best known are the White and Blue Sulphur Springs of Greenbrier County, the Salt and Red Sulphur, and the Sweet in Monroe County, Hot and Warm in Bath, Berkley in Morgan, Fauquier White Sulphur in Fauquier, Shannondale in Frederick, Alum in Rockbridge, Jordon's White Sulphur in Frederick, Red in Alleghany, Grayson in Carroll, Botetourt in Roanoke, Holston in Scott, Augusta Springs and Daggus Springs in Botetourt.

LESSON III.

LODORE WATERFALL.

RIVERS.

215. RIVERS commonly take their rise in springs, lakes, or the thawed ice and snow of elevated mountains. The smaller streams which unite to form them are variously called rills, rivulets, and brooks. Though rivers frequently rise in lakes, or spring from small elevations, the great storehouses from which the mightiest streams are fed are the ice-clad mountains of table-lands.

216. The basin of a river comprehends the entire country drained by it and its tributaries. The elevated land separating one basin from another is called the water

Questions.-211. Other kinds of mineral springs? 212. Mineral springs of the U. States? What noted springs in the State of New York? For what is Saratoga remarkable? 213. Which are the most celebrated springs at Saratoga? 214. Principal springs in Virginia? 215. Where do rivers commonly take their rise? What are the great storehouses from which they are fed? 216. What is the basin of a river? The water-parting or watershed? What elevated water-parting is mentioned? Have water-partings commonly a great elevation?

parting or watershed, of which the ridge of a house-roof affords an illustration. This is sometimes a lofty range of mountains, as the Alps, streams from which flow into opposite and distant seas. But commonly a water-parting has no great elevation, a slight rise of the surface being sufficient to separate streams whose mouths are thousands of miles apart. South America presents the rare example of two river-basins connected by a navigable natural channel. This is caused by the river Orinoco branching off in its upper course and proceeding by different channels to the sea.

217. South America is remarkable for containing the largest river-basin in the world, that of the Amazon measuring 2,275,000 square miles. Next to it, in point of extent, is the basin of the Mississippi and Missouri, in North America, measuring 1,333,000 sq. miles. The greatest river-basin in Asia is that of the Obi, 1,250,000 square miles; the greatest in Africa is that of the Nile, supposed to contain 1,240,000 square miles; and the greatest in Europe is that of the Volga, 528,000 square miles.

RedRiv. (I. &Cut Off

MISSISSIPPI R.

Raccourci Cut Off

218. The course of rivers is commonly winding. In some cases it is so tortuous that its actual length is three times that of a straight line drawn from its source to its mouth, as the Forth in Scotland; in others, as the Hudson,-it is mainly straight. The Mississippi River is remarkable for its windings, or bends, as they are locally called.

WINDINGS OF THE MISSISSIPPI.

219. In 1848 the Raccourci Cut-off, an artificial channel, was made in this stream a little below the confluence of the Red River. The distance, about 30 miles, in the old channel a common steamboat would be three hours in going round, and now one can run through the cut-off in ten minutes up, and in two or three minutes down. The passage was at first a narrow one, but it has become so widened and deepened by the force of the current that the largest trees of the forest will go down root foremost, and the tops of them will disappear.

220. The actual meanderings of the Missouri and the Mississippi, or the difference between the direct distance from the source of the former to the mouth of the latter and that by their channels, is estimated at 2,148 geographical miles. meanderings of the other principal streams, including that of their tributaries, is given approximately in the following table:

Rivers.
Rhine...
Elbe..
Rhone.
Dnieper..

Don..

The

Questions.-What rare example is mentioned of two river basins being connected by a navigable natural channel? 217. For what is South America remarkable? Exten: of the basin of the Amazon? Of the Mississippi and Missouri? The greatest river-basin in Asia, and its extent? In Africa, and its supposed extent? In Europe, and its extent? 218. What is said of the course of rivers? The Forth in Scotland? The Hudson? The Mississippi? 219. Raccourci Cut-off? 220. Meanderings of the Mississippi? Other rivers?

66

of rapids, falls suddenly to a depth of 153 feet. The cataract is divided by Goat Island into two parts. The largest of these, on the Canadian side, called the Horse-shoe Fall, from its shape, is 1,800 feet-more than one third of a mile-broad, and 153 feet in height. The fall, on the American side, is 600 feet in breadth and 164 feet in height. A cloud of mist points out the locality of the cataract, and under favorable circumstances its roar may be heard, it is said, at a distance of 40 miles.

FALLS OF THE MINNEHAHA.

222. The fall of rivers is the difference of level between their source and mouth: it varies, from a few feet to many thousands. That of the Volga, in Europe, amounts to only 633 feet in a course of 2,400 miles, about three and one eighth inches to a mile; on the other hand, the Ganges, in Asia, falls 13,672 feet in a course of 1,680 miles, or more than eight feet to a mile. It is in the upper courses of rivers, in mountainous or hilly regions, that the chief portion of fall is accomplished, while the lower courses have

a placid flow, suitable for navigation.

223. A rapid is a rush or fall of water where the bed of a river has a moderate inclination: a cataract is where it has a steeper descent, or a vertical depression. Falls formed by rivulets or mountain torrents receive the name of cascades.

224. Cataracts are among the most sublime objects of nature, the effect they produce on the mind of the beholder depending more on the volume of water than the distance of the descent. Though they are to be found in all countries, those of North America are by far the most extensive and picturesque.

225. The Falls of Niagara, in the river by the same name, which connects Lake Erie to Lake Ontario, constitute one of the greatest natural spectacles on the globe. The river, about three quarters of a mile wide, after forming a succession Questions.-221. How do the windings of rivers augment their utility? How must we regard this arrangement? 222. What is the fall of rivers, and how does it vary? What is that of the Volga? The Ganges? Where is the chief portion of fall accomplished?

WHITNEY JOCELYN&ANNIN SC

FALLS OF ST ANTHONY.

226. The Falls of St. Anthony, in the Mississippi, about 400 miles from its source, and just above the mouth of the St. Peters, stand nearly at the head of the navigation of that stream. They have a descent of from 17 to 20 feet, and aro thus described by a recent traveler: "Above the falls the river is about 600 yards in width. In its descent it is divided by Cataract Island, a high rocky mass, covered with trees and shrubbery., All around this island, above and below, are strewn huge masses of limestone rocks, heaped in Titanic confusion, and

attesting the mightiness of the water with which they seem to be contending."

227. Among the other noted falls in America are those of the Missouri, 500 miles from its source, a succession of rapids and cataracts, 26, 47, and 87 feet in perpendicular height; the rapids of St. Lawrence, above Montreal, extending about 9 miles; the Great and Little Falls of the Potomac, in Maryland; the Falls of Montmorenci, near Quebec, which descend 240 feet in an unbroken sheet; and the Cataract of Tequendama, in the environs of Santa Fé de Bogota, a magnificent fall of 574 feet.

FALLS OF MONTMORENCI.

Questions.-223. What is a rapid? A cataract? Cascade? 224. Where are the greatest cataracts? 225. What is said of the Falls of Niagara? Describe it. 226. Give particulars of the Falls of St. Anthony. 227. Other noted falls in America?