The navigable mileage of the Alabama rivers is 2000 m., but obstructions often prevent the formation of a continuous route, notably the "Muscle Shoals" of the Tennessee, extending from a point io m.
On account of the rapid fall of its tributaries, the union of so many of them with the main stream near its middle course and the obstructions to the flow of the water in the lower course, the Passaic is subject to disastrous floods.
Among the miscellaneous powers of an urban council with respect to streets may be mentioned the power to widen or improve, and certain powers incorporated from the Towns Improvement Clauses Act 1847, with respect to naming streets, numbering houses, improving the line of streets, removing obstructions, providing protection in respect of ruinous or dangerous buildings, and requiring precautions to be taken during the construction and repair of sewers, streets and houses.
These relate to obstructions Hackney and nuisances in streets, fires, places of public resort, hackney carriages and public bathing.
Precisely the same thing happens in the actual crust of the earth, except that, in the formations usually met with, the strata are so irregularly permeable that no such uniform percolation occurs, and most of the water, instead of oozing out near the sea-level, meets with obstructions which cause it to issue, sometimes below the sea-level and sometimes above it, in the form of concentrated springs.