Читать книгу Inventors at Work, with Chapters on Discovery - George Iles - Страница 24

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Wood as commonly hewn, sawn, and planed; bricks as usually molded; stone as it leaves an ordinary hammer, all have flat sides and square edges. Hence it has been easiest to build walls and floors which meet at right angles, and to leave sharp corners on outer walls, windows, doorways, and chimneys. This is being changed for the better; in staircases the boards on which we tread and those which join them together now meet in smooth curves; so do the walls of rooms as they reach ceilings and floors, conducing to ease and thoroughness in sweeping and cleansing. In outer walls, in doorways and windows, similar curves reduce liability to hurt and harm. A wagon wheel easily knocks pieces from an angle of brickwork; it makes little impression on bricks retiring from the street line in a sweeping curve, as in the Madison Square Garden, New York. Factory chimneys have long been built round instead of square; to-day in the best designs the ducts to a chimney are also freely curved. In blast furnaces this is the rule for every part of the structure, ensuring gain in strength, lessening resistance to the flow of gases, and thus saving much fuel. When waterpipes varying in diameter are joined, the junction should be a gradual curve, otherwise retarding eddies will arise, wasting a good deal of energy; the same precaution is advisable in laying pipes for steam or gas. The elbows of pipes for gas, steam or water exert the least possible friction when given the utmost feasible radius. All the various parts of heavy guns are curved, since any sharpness of angle at a joint brings in a hazard of rupture under the tremendous strains of explosion.

Corner Madison Square Garden,

Madison Avenue and 26th Street,

New York.

Two pipes with funnel-shaped junction.

Embossing and stamping machines may either decorate a sheet of note paper or make a tub from a plate of steel. Whatever their size these machines have the edges of their dies nicely rounded, so as to avoid tearing the material they fashion. To ensure the utmost strength in the machines themselves they are contoured in ample curves. In hydraulic presses, subjected to strains vastly greater, the same shaping is imperative, otherwise a cylinder may part abruptly with disastrous effect. So, too, in the manufacture of magnets and electro-magnets, their terminals are well rounded to ensure the closest possible approach to uniformity of field and of working effect.

A glance at a warship discovers her varied use of curves in defence; to deflect assailing shot and shell, her plates are given bulging lines, her turrets are built in spherical contours, and her casemates are convex throughout. On much the same principle fortifications are rendered bomb-proof, or rather bomb-shedding; while outworks are so inclined that bombs fall to distances at which they do little or no harm. As in war so in peace; there is gain in building breakwaters with an easy curve; to give their masonry and timbers a perpendicular face would be to invite damage, whereas a flowing contour like that of a shelving beach, slows down an advancing breaker and checks its shock. In rearing lighthouses to bear the brunt of ocean storms the outline of a breakwater is repeated to the utmost degree feasible. Often, however, the base supporting a lighthouse is too small in area for such an outline to be possible.