THE APPLICATION OF MACHINERY.

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tion of the slide, and completed it in the spring of,1318.

“ The Slide of Alpnach is formed entirely of about2.5,000 large pine trees, deprived of their hark, andunited together in a very ingenious manner, withoutthe aid of iron. It occupied about 160 workmenduring eighteen months, and cost nearly 100,000francs, or 4,250Z. It is about three leagues, or44,000 English feet long, and terminates in the Lake of Lucerne . It has the form of a trough, about sixfeet broad, and from three to six feet deep. Itsbottom is formed of three trees, the middle one ofwhich has a groove cut out in the direction of itslength, for receiving small rills of water, which areconducted into it from various places, for the pur-pose of diminishing the friction. The whole of theslide is sustained by about 2,000 supports ; and inmany places it is attached, in a very ingenious man-ner, to the rugged precipices of granite.

“ The direction of the slide is sometimes straight,and sometimes zig-zag, with an inclination of from10 to 18°. It is often carried along the sides ofhills and the flanks of precipitous rocks, and some-times passes over their summits. Occasionally itgoes under ground, and at other times it is con-ducted over the deep gorges by scaffoldings 120 feetin height.

“The boldness which characterises this work, thesagacity displayed in all its arrangements, and theskill of the engineer, have excited the wonder ofevery person who has seen it. Before any stepcould be taken in its erection, it was necessary tocut several thousand trees to obtain a passageQ