Page:Popular Science Monthly Volume 27.djvu/736

716 on the simplest principles of physiology, that other essential organs, such as the skin and kidneys, are relieved by the transference of part of their excretory function to the bowel and act with greater ease, the general vascular system is lightened by this regulating drain, and its faculty of absorbing the waste products of food and work is encouraged in proportion." Only persons of gouty and rheumatic habit, or of tendencies to diarrhoea, dysentery, or saccharine diabetes, will be likely to find fruit in any moderate quantities to disagree with them, while dyspeptic persons will find it almost wholly beneficial.

Formation of Peat.—For the growth and formation of peat—which is vegetable matter in a semi-decomposed state—is required a climate sufficiently moist to foster the growth of the plants of the remains of which it is composed, and at the same time cool enough to retard, under certain conditions, the decomposition, beyond a certain point, of successive generations of those plants. Accordingly, we find it most abundantly distributed in latitudes above 45 in either hemisphere. In Ireland, the peat bogs cover about one seventh of the surface. Peat-bogs are classified as those which have ceased to grow and those which are still growing. Some of the former class must be of enormous age. In many bogs in Ireland the deposit is from fifteen to thirty feet deep, and in Scotland this depth is frequently exceeded. Each year's growth, according to Mr. Kinahan, is represented by a layer of lamina, and these lamina are, on an average, in white turf one hundred, in brown turf two to three hundred, in black turf from six to eight hundred to the foot. It is easy with these data to compute approximately the probable age of the bogs; but the result of the calculation is liable to variations according to the manner in which the bog was formed; for the rate of growth is subject to many fluctuations, not only in different bogs, but in different parts of the same bog. When two layers of wood are found in peat, the lower forest usually proves to have consisted of oak, and the upper one of pine. Remains of the great Irish deer are very common in the bogs of Ireland, and human relics are often found. No chronological estimates can, however, be based upon the presence of such relics, for articles having weight will easily sink through the soft mass. In districts where peat is plentiful it is extensively used for fuel, for which purpose the turf is cut from the bogs in narrow rectangular masses a foot or eighteen inches long, and prepared by drying. It is not well adapted for use in manufactures, for its heating power is low. Peat-charcoal has, however, been used with advantage in smelting iron, and it possesses very powerful antiseptic and deodorizing properties. Considerable quantities of peat-land have been reclaimed and brought under cultivation. In its natural state the soil is sour and unfit to promote plant-growth, but when drained and treated with lime it may be brought to a high degree of fertility. When the peat-bog is situated near to limestone, the process of reclaiming the land is cheap and the result is profitable.

A Scientific Commonplace-Book.—The purpose of "The Scientific Roll," a new serial kind of encyclopædia, or commonplace-book, projected and begun by Mr. Alexander Ramsay, is to cull, classify, and embody in a shape conveniently accessible, all the important statements of fact and theory that now lie scattered and substantially out of reach to any one man in the six thousand scientific periodicals of the day. The systematization of notes on this plan results in a most compendious classification of all that is wanted in scientific literature, in such a way that lines of thought are suggested to the reader, and facilities are offered for following them out which books, as a whole, do not afford. No correction is given, or comment upon the views of the several authors, but each one speaks for himself, and the reader is left to choose to what he will hold. The first volume, just published by Swan, Sonnenschein & Co., London, includes the literature of climate, in which a prominent place is given to a very interesting bibliography. One of the oldest works catalogued is said to have been written in the thirteenth century, and was printed by Caxton, under the title of "Image or Mirror of the World." But, as an English journal admits in its review of the publication, "it is not till