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1840 · Bellford · "Combining Glass with Metal for Use in Parts of Structures and Pavements where Translucent Medium desirable" · Page 3 Home  > Prism Glass  > Patent Index  > Page 3

1,840: 3 of 9

	A.D. 1853.--Nº 1840.	3
Bellford's Improvements in the Combination of Glass with iron, &c.     Fig. 14, is a section of Fig. 12.     Fig. 15, is an edge view of the same light, with the packing ring in section.     Similar letters of reference indicate corresponding parts in each of the different Figs. in which they are used.     A, A, (see Figs. 1, 2, and 3,) are gratings of cast iron, having a number of circular openings, each of which is surrounded by a rebate a, (see Fig. 3,) on the upper or outer side, the said rebate being a little enlarged at the back, and thus giving the sides a form of a hollow frustum of a cone.     B, B, are the glass lights, which fit in the rebate in A, A, and are therefore of circular form, and in order to prevent their being withdrawn from the rebates they are made conical, the back part being the largest, and just small enough to pass through the front or smaller part of the rebate. This causes an annular space to be left between the glass and the sides of the rebates when the glass is in place, and this space is intended to receive the cement which is to hold the glass in place. It is not absolutely necessary to enlarge the rebate at the back or bottom, as the roughness of the casting will be sufficient to hold the cement if the sides of the rebate are parallel.     C, D, (see C, Fig. 7, and 9, and D, in Figs. 10, and 11,) are hexagonal shaped glasses, which are intended to fit in hexagonal openings and rebates; their sides may be made parallel or tapering, like those B, B, and the rebates of the gratings intended to receive them will be similarly enlarged or tapered at the back. All the above glasses with tapered sides are intended to be secured in place with cement. The forms of the glasses may be varied indefinitely.     The cement which I prefer to employ, for the reason that after a series of experiments I have found it best for the purpose, is a mixture of one part of coal tar by weight and two parts sulphur. I mix the coal tar with the sulphur in a powdered state, and when I use it I warm the mixture till it aquires a sufficient degree of fluidity to run freely. I then lay the gratings in a horizontal position, with the face and the rebates upwards, and insert the glasses, raising them by any convenient means above the bottom of the rebates, so that the cement will