Page:Popular Science Monthly Volume 35.djvu/443

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cept these consequences? Prof. Drummond prefers a theory of great northern elevations of land creating mountain-chains and their glaciers, accompanied or followed by a depression farther south, which admitted the arctic currents, or perhaps formed an inland sea and a highway for icebergs bearing débris and bowlders, which they dropped on the bottom.


Orchids.—Orchids are commended by Mr. Frederick Boyle as pleasant room-ornaments, and clean, easily managed plants. "Observe my Oneidium," he says; "it stands in a pot, but this is only for convenience—a receptacle filled with moss. The long stem, feathered with great blossoms, springs from a bare slab of wood. No mold nor peat surrounds it; there is absolutely nothing save the roots that twine round their support, and the wire that sustains it in the air. It asks no attention beyond its daily bath." Sir Trevor Lawrence can see no reason, in the case of most orchids, why they should ever die. "The parts of the Orchideæ are annually reproduced in a great many instances, and there is really no reason why they should not live forever, unless. . . they are killed by errors in cultivation." Another authority says that, "like the domestic animals, they soon find out when there is one about them who is fond of them. With such a guardian they seem to be happy, and to thrive, and to establish an understanding, indicating to him their wants in many important matters as plainly as though they could speak." According to Mr. Boyle, the secret of orchid culture lies in their indifference to detail "Secure the general conditions necessary for their well-doing, and they will gratefully relieve you of further anxiety; neglect those general conditions, and no care for detail will reconcile them." In Mr. Sander's orchid farm, at St. Albans, England, where three acres are occupied by orchids exclusively, growing in the most profuse luxuriance, no great pains are taken to exclude frost from the cool houses. It would be better to keep them at 50°, but the advantage does not equal the expense and inconvenience of warming such enormous buildings to the requisite degree. Mr. Boyle says that the "Indians of tropical America cherish a fine orchid to the degree that, in many cases, no sum, and no offer of valuables, will tempt them to part with it. Ownership is distinctly recognized when the specimen grows near a village." Mr. Roege has left a description of the scene when he first beheld the Flor de Majo. The church was hung with garlands of it, and such emotion seized him at the view that he choked. The natives showed him plots of this species acres in extent, where it was grown for the ornamentation of their church. A fine Cattleya Morsiæ in one of Mr. Sander's houses—the largest orchid of the kind that was ever brought to Europe—had grown upon a high tree beside an Indian's hut, and belonged to him, as it had belonged to his grandfather. He refused to part with it at any price for years, but was overcome at last by a rifle of peculiar fascination, added to the previous offers. "A magic-lantern has great influence in such cases, and the collector provides himself with one or more nowadays as part of his outfit."


Etching on Glass.—The object to be etched is immersed in a bath of melted wax, which on removal forms a thin coating over its surface. On this the designs are carefully scratched out by means of a pointed instrument, which removes the wax along the lines of the pattern. The glass is then immersed in a solution of hydrofluoric acid. The acid, which is very corrosive, attacks all the portions of the glass not protected by the wax, thus eating out the lines of the engraving on the glass. When this is done, all that remains is to clear away the wax. Owing to the destructive nature of hydrofluoric acid, a special room is kept, in which it is applied, the windows of which must be coated with wax, and the vessels used to contain the acid must be made of lead. Monograms and similar designs are printed in a kind of thick ink, on transfer paper, the lines of the monogram being left uncovered by the ink. The pattern is then transferred to the glass, the ink protecting the portions covered from the acid in the subsequent processes. As, however, the monogram only covers a small portion of say, a wine-glass or decanter, the rest is coated with wax. The bath of hydrofluoric acid is then used as before. The pretty zigzag patterns which so frequently adorn many wine-glasses are scratched on the wax by means of several ingenious machines.