Page:Popular Science Monthly Volume 41.djvu/153

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must throw salt on the fire, and then put an egg in the hen-house in prayerful hope that a considerate fowl may sit on it; in February all the dogs must be thoroughly beaten as a precaution against hydrophobia—indeed, there is always some ceremony to the fore, generally accompanied by songs and ballads." To the Greek, too, every accident has its interpretation. To drop oil is unlucky, but wine may be spilt with advantage; a rainbow over a cemetery means a coming epidemic; and the recipe concerning "the hair of the dog that bit you" is practically enforced by inserting tufts of the dog's hair in the wound made by his teeth.


India-rubber Trees.—India-rubber trees, according to W. R. Fisher, in Nature, are extensively cultivated in flourishing plantations in the Charduar forest, at the foot of the Himalaya Mountains, in Assam. The climate of the place is essentially damp. The forest contains a great number of woody species, both evergreen and deciduous, with a few enormous old rubber trees disseminated through it. Trees have been measured here 129 feet high, with a girth around the principal aërial roots of 138 feet, while the girth of the crown was 611 feet. As rubber trees can not stand shade, and the seeds damp off unless fully exposed to light and well drained, the natural reproduction of Ficus elastica generally takes place in the forks of stag-headed or lightly foliaged trees high up in the crown, where the seeds are left by birds; and from such a site the aerial roots in process of time descend to the ground and develop into a vast hollow cylinder around the foster-stem, and it is speedily inclosed and killed by the vigorous crown of the epiphyte, which eventually replaces it in the forest. In its epiphytic growth the aërial roots of Ficus elastica may take several years to reach the ground, but, once well rooted, nothing can probably surpass it in its native habitat for rapidity of growth and vigor. At first attempts were made to propagate by cuttings, which struck easily; but it was soon discovered that rubber seed germinates freely on well-drained beds covered with powdered charcoal or brick-dust, and that the seedlings, though at first as small as cress, grew rapidly, and became about two feet high in twelve months, and were much hardier against drought than plants produced from cuttings. The base of the stem of the seedlings swells out like a carrot, and this probably enables them to tide through the dry season in safety.


Tin Production of Cornwall.—A review, by Mr. J. H. Collins, of the tin production of Cornwall during seven centuries shows how rapidly it has grown. An extensive commerce in the metal was already carried on in extremely ancient times. In the thirteenth century of our era, 486 tons of tin were taken annually from the mines; in the fourteenth century, 828 tons; in the fifteenth century, 732 tons; in the sixteenth century, 802 tons; in the seventeenth century, 1,300 tons; in the eighteenth century, 3,938 tons; and in the nineteenth century (ninety years), 8,795 tons. The total quantity raised is not less than 1,938,800 tons. The mean average for the fifty years ending in 1849 was 6,008 tons per year, and for the fifty years ending in 1889, 12,278 tons per year. This remarkable increase during the last forty years has been in the face of extensive production in the Strait of Malacca and Australia. Of sudden advances in production, the most noticeable, in the latter part of the fourteenth century, was probably occasioned by the great demand for bell-metal. The second period of rapid advance was in the latter part of the eighteenth century, when bronze was commonly used for cannon. The third period is that of the general use of tinned metals.



Involuntary Movements.—The article on Involuntary Movements, by Prof. Jastrow, published in the April number, will appear in a more extended form in the forthcoming issue of the American Journal of Psychology.

A promising account is given of the copper mines of French Congo. They lie in the district around the source of the Ludima-Niadi, about two days south of Stéphanieville. The ore, a malachite, is brought to the surface by about three hundred and fifty negroes, whose methods of work are extremely simple. They reach the mineral by digging out, with implements of hard wood, holes or shafts three feet wide and twice as deep. The malachite is broken on the ground, and afterward when pulverized is put into a furnace on a tray with charcoal,