The Boston School Atlas, Embracing a Compendium of Geography

by B. Franklin Edmands

These works are ingeniously constructed at Fair Mount on the eastern bank of the river. The water is raised by the action of an engine, moved by the water power of the river itself, and deposited in large reservoirs, from whence it is conveyed by iron pipes to every part of the city. The aggregate length of the pipes already laid exceeds 63 miles. Three reservoirs have already been constructed which contain ten millions of gallons, and a fourth has been commenced which will contain ten millions more, being a quantity sufficient for the use of the city Philadelphia ten days.

LAKES.

Lakes are of four distinct classes.

1. Those which have no streams of water running into nor from them. They are generally very small, and of little consequence.

2. Those which have streams flowing from them, but none flowing into them. These are mostly supplied with water from subterraneous springs. Some of this class form the sources of large rivers, and are generally situated on elevated land.

3. Those which have streams flowing both into and from them. These, by a continual flow of fresh river water, preserve their clearness and sweetness; and often, besides the river which seems to flow through them, have sources of their own near their shores, or from springs at their bottoms.

4. The fourth class is ranked among the phenomena of nature. They have no visible outlet, but receive the waters of rivers which flow into them. The Caspian sea, in Asia, is an instance of this kind. These lakes probably lose the surplus of their waters by evaporation produced by the heat of the sun.

The waters of lakes which receive their supply from springs and rivers, partake of their qualities. There are some lakes whose waters are exceedingly clear and transparent. Lake Wetter in Europe is so limpid that a piece of money can be seen at the bottom at 120 feet depth.

CAVERNS.

In many parts of the earth are found caverns, or deep cavities and grottoes, which are remarkable on account of their great extent, and for the grand and imposing appearance of the rocks which compose the sides and roof.