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243,266 · Hyatt · "Concreted Illuminating-Grating" · Page 2 Home  > Prism Glass  > Patent Index  > Page 2

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time fluid, the glass meets with no resistance to its expansion, and consequently does not break, the result of this reheating of the glass under these favoring conditions being in effect a perfecting of the original annealing, so that the glass, in place of being injured, is improved by the process; but when the same glasses are placed in the perforated metal plate and surrounded with hydraulic cement or concrete in its cold, moist, and pasty condition, the first effect is to chill the glasses, after which, as the chemical change called "setting" takes place, heat commences to be generated slowly around the peripheries of the glasses, the immediate effect being a slight expansion of their exteriors, the central portions remaining substantially unaffected, the result of this molecular disturbance being a number of imperceptible but real strains within the body of each glass weak enough to be so affected.     The next stage in this process of forming fractured glasses is when the plastic concrete becomes sufficiently hard to resist the expansion of the glasses, for the tendency of the glasses to enlarge by expansion continues after the setting of the concrete in probably even greater degree than before, the maximum of concrete heat being reached after the setting. The effect of boiling coal-tar and molten lead is to bring the glasses to their maximum of expansion before the congealing of the fluid around them, the molecular forces in the glasses tending thereafter in contraction to the centers of the glasses; but with the concrete the operation is all the other way. The glasses are in time very act of expanding and in course of reaching their maximum at the moment when the plastic mass becomes suddenly solid around them. The incipient molecular strains, by this sudden check to the expansion of the glass, become greater, in addition to the new ones thus suddenly created. When gratings containing glasses such as these are laid in position in the public footways and exposed to concussions and to the vibrations incident to the footfalls of a multitude passing over them, it is easy to see how and why an apparently universal fracture of the glasses should suddenly appear; and although the final and obvious fracture lo may be due to the final and last man who passed over the glass, the actual and primal cause must be referred back to the "original sin" of the glass-works.     My improvements in concrete-light manufacture based upon the foregoing theory are as follows, viz: first, the employment of glasses got out of the plate glass or plate-glass material, or from flint-glass metal, which have been annealed by or according to the plate-glass method of annealing, or by the toughening process of La Bastie, or a method analogous thereto, for combination with plastic concrete as substitutes for the flint glasses now employed in such manufacture; second, employing flint glasses made in the ordinary way in connection with means and processes to prevent the generated heat of the concrete from injuring

the glasses surrounded by it during the period of its setting and hardening. These two modes I claim as my invention.     In the use of plate-glass the ragged edges of the small pieces required to be cut from the plates are objectionable. I prefer, therefore, to get them out of plates partially cut through by suitable means at the time the plates are made, as set forth in my English patents for the same, a mode not necessary for me to describe here, my present claims being to the combination of such glass with concrete. For a like reason I describe no special form or construction of oven for producing a perfectly-annealed flint-glass, the requisite of such an oven being an undisturbed temperature of proper character during the annealing of the glasses, a mechanical possibility within reach of the glass-maker, but not immediately important to me, my invention herein being confined as to what I claim-- to the combination of flint-glasses so annealed with concrete in the making of concrete lights; in the employment of flint-glasses, as usually made and annealed, and to the means I propose for preventing breakage of same when set in plastic cement.     According to one part of my invention, my improvement consists in the employment of glasses formed with bulging sides, in form resembling the frustums of two cones put base to base, otherwise called "globate." Glasses of this shape I employ either nakedly or belted with lead, in combination with concrete, the same being employed in the usual manner of setting glasses in plastic concrete in the making of concrete lights.     According to another part of my invention, my improvement (whatever the shape of the glasses) consists in warming, heating, and expanding the glasses before combining them with the concrete, a convenient mode of doing this being by means of a water-bath, into which the glasses are placed, the temperature of the water being then gradually raised to the required point of 100° and upward, the concrete of preference being at the same time made with tepid rather than with cold water. The mode of procedure is then the same as in the ordinary making of concrete lights, any hair-cracks about the glasses that may be discovered when the work is finished being made good by grout.     According to another part of my invention, my improvement consists in the employment of water-baths, into which the concrete lights are placed and submerged the moment they are made, the purpose of the water being to carry away from the glasses the generated heat of the concrete, the water at the same time tending to improve the character of the concrete. These water-baths I make to suit the size and shape and number of gratings designed to be placed in them. The gratings are to remain in the bath until the concrete has become cold; but they may remain with advantage for several days.     According to another part of my invention,