Page:Popular Science Monthly Volume 23.djvu/882

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THE POPULAR SCIENCE MONTHLY.

means of escape is given it, and the fireplaces furnish that. The course of the air entering the room from the heating apparatus is to rise to the ceiling and spread out there. It then descends along the sides of the room exposed to the open air, and is withdrawn by the fireplace if there is any which thus serves to facilitate the distribution of the heat in the lower part of the room. If the opening in the chimney is near the ceiling, the warm air will go out there without descending to the floor. It is important, in providing cold-air inlets for any kind of heating apparatus, to see that they take the air from a point where it is pure. They should also take it from the north or northwest, for the coldest winds come from that direction, and the heating of the house at such times is made much more convenient and safe if the prevailing draughts are made to assist it. If the inlets are on the south side of the house, the furnace is liable to be supplied, as is sometimes the case, with air from the northern rooms, entering the house through window-cracks or down a cold chimney, and sending the heated air out through the cold-air box into the back yard. There are limits, and they are not very wide, to the horizontal heating capacity of the best furnaces. Hence, if the ground-plan of the house is extensive, two or more furnaces should be provided rather than to depend upon one. Steam and hot-water apparatus are better horizontal distributors of heat than hot-air furnaces. As between the two, Mr. Philbrick prefers the hot-water apparatus as more easily managed, and more adjustable to mild temperatures, though its first cost is greater than that of steam apparatus. With either, the main dependence for heat should be upon air that has been heated by passing through the apparatus, rather than by direct radiation from pipes or surfaces in the rooms, which should be used only as auxiliaries.

 

Long Days and Plant-Growth.—The Norwegian plant-geographer, Schübeler, a short time ago called attention to some striking and surprising peculiarities manifested by vegetation in high latitudes, which he ascribed to the intensive light-effects of the long days. Most plants in these regions produce much larger and heavier seeds than in lower latitudes; and the difference is in some cases astonishing. Dwarf beans taken from Christiania to Drontheim gained more than sixty per cent in weight; and thyme from Lyons when planted at Drontheim showed a gain of seventy-one per cent. Grain is heavier in the north than in more southern latitudes; and Norwegian seed planted at Breslau fell off greatly in the first year. Another remarkable fact is that the increase of weight in northern latitudes takes place through the assimilation of non-nitrogenous substances, while the protein products have no part in it. The leaves also of most plants grow larger in high latitudes, and at the same time take on a deeper, darker color. This peculiarity, first noticed by Grisebach and Martins, has been observed not only in most of the wild trees and shrubs, but also in fruit-trees, and even in kitchen garden plants. It has further been observed that the flowers of most plants are larger and more deeply colored, and that many flowers which are white in the south become in the far north violet.

 

Brain-Work under Pressure.—A writer in "The Journal of Science," on "Cram and its Amenities," only utters a truism when he remarks that brain-work is not per se physically injurious, but that, when kept within reasonable bounds and right conditions, it appears distinctly favorable to health and long life. He enforces the fact by some happy illustrations. An essential condition to the prosecution of brain-work without injury is that the organ must be sufficiently mature before it is subjected to much exertion; hence, it is disastrous to crowd the brains of children. Another important condition under which study is wholesome "is freedom from anxiety, hurry, and worry. This condition is admirably illustrated in the career of almost all great investigators of nature. Woehler (who died at eighty-two), for instance, contributed no fewer than two hundred and twenty-five memoirs to the scientific journals or to the transactions of learned societies. Almost all of these papers are of great value, and many of them embody the outcome of months of careful and delicate experimentation. But in no one case was he compelled to finish any of