[Continued from page 390 ] Indications of the Weather as shown by Animals, Insects, and Plants,—A very interesting paper on this subject was read by W. B. Thomas, of Cincinnati. " When a pair of migratory birds have arrived in the spring, they immediately prepare to build their nests, making a careful recon-noisance of the place, and observing the character of the season that is cot ing. If it be a windy one they thatch the straw and leaves on the inside of the nest, between the twigs and the lining; and if it be very windy they get pliant twigs and bind the nest firmly to the limb, securing all the small twigs with their saliva. It they feor the approach of a rainy season, they build their nests so as to be sheltered irom the weather. But If a pleasant one, they build in the fair, open place, without taking any of those extra precautions. But insects and smaller animals furnish us with the best means ot determining the weather. Snails do not drink, but imbibe moisture in their bodies during a rain. At regular periods after the rain they exude thi moisture from their bodies. Take, for example, the " Helix Alternata;' the first fluid exuded is the pure liquid. When this is exhausted, it then changes to a light red, then deep red, then yellow, and lastly to a dark brown. The Helix is very careful not to exude more of its moisture than is necessary. It might exude it all at once, but this is not in conformity to its general character, as this would prove too great an exertion. The Helix alternate is never seen abroad, except before a rain, when we find it ascending the bark of trees, and getting on the leaves. The Helix, Arborea, Identata, Ruderati, and Minuta, are also seen ascending the stems, of plants .two days before a rain. The Helices Clausa, Ligera, Pennsylvania and elevata generally begin to crawl about two days before the rain will descend. T'iey are seen ascending the stems of plants. If -it" be a long and hard rain, they get on the sheltered side of the leaf, but if a short one they get on the outside. The Luccinea have also the same habits, differing only in color of animals, as before the rain it is of a yellow color, while after it is a blue. For a tew days before a rain, a large and deep indentation appears in the H. Thyroide-us, beginning on the head between the horns, and ending with a jointure at the shell. The Helices Solitaria and Zeleta, a few days before a rain crawl to the most exposed hillside where, if they arrive before the rain descends, they seek some crevice in the rocks, and then close the aperture of the shell with glutinous substance, which, when the rain approaches they dissolve, and are then seen crawling out. The leaves of trees are even good barometers ; most of them for a short, light rain, will turnup so as to receive their fill of water; but lor a long rain, they are so doubled as to conduct the water away. The Rana, Bufo and Hyla, are also sure indications of rain, for, as they do not drink water, but absorb it into their bodies, they are sure to be found out the time they expect rain. The Locuta and Gryllus are also good indicators of a storm. A few hours before the rain they are to be found under the leaves ol trees and in the hollow trunks." RisiNG of Water in Springs before Rains.—An interesting paper on this subject war read by Prof. Brocklesby, of Conn. " In the westward portion of the town oi Rutland, Vt., is a lofty hill, rising to the height of about 400 feet above the Otter Creek valley. Near the summit of the hill a small spring bursts forth, the waters of which are conveyed in wooden pipes to the barn yards ot two farm-houses situated on the slope of the hill; the first being about a quarter of a mile distant from the spring, and the second nearly one-third of a mile. At the latter house Prof. B. once resided. The waters of the spring are not abundant, and during the summer months frequently fail to supply the aqueduct. Such was the state of the spring when he arrrived at Rutland, for the summer had been extremely dry, the brooks were unusually low, and the drought had prevailed so long that even the famed Green Mountain had in many places begun to wear a russet livery. The drought continued, not a drop ot rain falling, when one morning the servant, coming in from the barnyard, affirmed that we should soon have rain, as the water was flowing in the aqueduct—the spring having risen several inches. The prediction was verified, for, within two or three days, rain fell to a considerable depth. In a short time the spring again sank low, and ceased to supply the aqueduct; but one cloudless morning, when there were no visible indications of rain, its waters once more rose—flowing through the entire length of the aqueduct—and ere twenty-four hours had elapsed, another rain was pouring down upon the hills. On inquiry, it was ascertained from the residents in the vicinity that the phenomenon was one of ordinary occurrence, and that, for the last twenty years, the approach of rain was expected to be indicated by the rising of the spring. Interested by these facts he sought for others of the like nature, and requested through the public prints information on this subject tromall who happened to possess it,—and also collateral points which were conceived to have important relation to this phenomenon. He was rewarded by the knowledge of only one additional instance, existing in Concord, Mass., where a, spring: thati supplies a certain brook is said to rise perceptibly before a storm. Mr. Munroe, who lives near the stream, afforded the following information:— lt The subject has not, so far as we are aware, fallen under the notice of any close observer of the facts you inquire about; the most that is known being this : that the bed of the brook, during a long drought, having become dry, the stream is ' known to start again before any rain, and the belief is that rain Is to be looked for immediately upoiriihe appearance of Dodge's Brook." The cause ot this phenomenon has been at-tributeft by some, to the fall of rain at distant sources oithe spring previous to its descent in the vicinity of the spnng itself; but he..believed the true solution was to be tound in the diminished atmospheric pressure which exists before a rain. The waters of a spring remain at any given level, because the atmospheric and hydrostatic pressure combined, exactly counterbalance the upward force of the jet. The spring will, therefore rise either when the force of a jet is increased, while the atmospheric pressure continues the same, or when the latter is diminished, while the former remains constant; and the elevation is greatest of all when the decrease in the density of the atmosphere occurs simultaneously with an increase in the strength of the jet. If the explanation given is correct, we arrive at the curious discoveries that the springs and fountains of 1 he earth are natural barometers, whose indications may, perhaps, be worthy of notice in future physical investigations.
This article was originally published with the title "American Assuciation for the Advancement of Science"