. Machinery and processes of the industrial arts, and apparatus of the exact sciences. and beauty by , Alvergniat, Gaiffe, and Seguy; and also at a late period byGeissler himself. Though there were many novel patterns, the appa-ratus itself presented no points of novelty, unless an exception be madein the case of the miners electric lamps, which are simply Geisslerstubes adapted to a useful and an important purj)ose. These lamps arerecommended by their entire safety, and by the fact that they requireno trimming. DE LA RIVES AURORA BOREALIS. The most interesting of all the forms
. Machinery and processes of the industrial arts, and apparatus of the exact sciences. and beauty by , Alvergniat, Gaiffe, and Seguy; and also at a late period byGeissler himself. Though there were many novel patterns, the appa-ratus itself presented no points of novelty, unless an exception be madein the case of the miners electric lamps, which are simply Geisslerstubes adapted to a useful and an important purj)ose. These lamps arerecommended by their entire safety, and by the fact that they requireno trimming. DE LA RIVES AURORA BOREALIS. The most interesting of all the forms of apparatus exhibited, designedto illustrate the relations of light to electricity, was a combination pre-sented by the society for the construction of physical apparatus ofGeneva, and invented by Mr. De La Rive, in which are reproduced inminiature all the most striking phenomena of the aurora borealis. Thisapparatus consists of a hollow sphere of wood, designed to representthe earth, which contains an electro-magnet occupying the position of36 i A 562 PAEIS UNIVERSAL the axis, while the polar regions are crowned by two bell-glasses fixed air-tight to the sphere. The arrangement is shown in Fig. 119, in which Fig. 119. B is the sphere, supported on afoot, and C C arethe bells areattached to thesphere by tworings of metal in-dicated by the let-ters / /. At aand b are stop-cocks, which per- De la Rives Auroral Apparatus. mit the bells to be exhausted by communication with an air-pump. The electro-magnetis concealed within the sphere, the soft iron core reaching only to theplane of the circles/ and f; but it is lengthened by means of two softiron cylinders of similar cross-section, which are insulated from it byinterposed plates of mica. These- cylinders, marked P and P, are inmetallic communication with the corresponding rings / and /. Fromeach of the two stop-cocks proceeds a stirrup-shaped wire, e, which car-ries a ring, A, of brass gilded. The
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Keywords: ., bookcentury1800, booksubjectmachinery, booksubjectscientificappa
