A novel and very admirable idea is in process of being carried out at Tarry-town, on the Hudson. About one hundred acres of ground, adjoining Sleepy Hollow - made memorable by Irving's pen - have been converted into a park, which, when finished, will contain carriage drives of several miles in extent, neatly kept walks for promenaders, and spacious lawns and sloping terraces where children can play and gambol. Within this park are villa sites, from one or two to six or eight acres in extent, which are for sale; and each purchaser will not only possess a charming homestead, but, also, be guaranteed all the privileges of the park, which ground will be for the use and benefit and under the control of the owners of the sites. It is scarcely necessary to speak of the natural scenery which surrounds this park - enough to say that it commands extensive views of three counties, and of the entire, sweep of the Hudson for several miles.

This system of united effort will become the custom when its advantages are more disseminated.

Rain is derived from a permanent source, viz., the waters of the globe, and chiefly the ocean, whence it is raised by evaporation, occasioned principally by the action of the sun's rays. The air is the vehicle in which it ascends in the state of invisible vapor, and the higher the temperature of the air the more vapor it will carry. Thus, at 66° Fahrenheit, each cubic foot of air will hold in solution fully seven grains of water; but at 45°, little more than half that quantity. It is therefore evident that if air at the former temperature, and completely satu-ated, be cooled by contact and mixture with colder air, the same quantity of moisture can no longer be maintained. If the warmer and colder portions have each as much moisture as they can carry, and if that at 66° should be cooled down, say to 45°, it must then part with half its load, unless the cold air mixing with the warmer is in a comparatively dry state, and then a portion at least of the superfluous moisture will be absorbed.

The general theory of rain may be expressed in a few words: it is vapor raised by heat and condensed by cold. In fact, the Huttonian theory, the one mostly approved, amounts to this. Some, however, attribute a considerable share of the process to electricity.