Pressed Prism Plate Glass Co. v. Continuous Glass Press Co.

150 F. 355, 1907 U.S. App. LEXIS 4932
CourtU.S. Circuit Court for the District of Western Pennsylvania
DecidedFebruary 1, 1907
DocketNo. 14,
StatusPublished
Cited by2 cases

This text of 150 F. 355 (Pressed Prism Plate Glass Co. v. Continuous Glass Press Co.) is published on Counsel Stack Legal Research, covering U.S. Circuit Court for the District of Western Pennsylvania primary law. Counsel Stack provides free access to over 12 million legal documents including statutes, case law, regulations, and constitutions.

Bluebook
Pressed Prism Plate Glass Co. v. Continuous Glass Press Co., 150 F. 355, 1907 U.S. App. LEXIS 4932 (circtwdpa 1907).

Opinion

ARCHBALD, District Judge.1

The patents in suit relate to the manufacture of plate prism glass; that is to say, glass in sheets or plates, having transverse parallel projections, or ribs, upon one side, in the form of prisms, a character of glass extensively used to illuminate the interior of buildings darkened by adjoining structures. There are three patents involved — one for the machine or apparatus by which the glass is made; another for the method or process; and [356]*356tbe third' for the manufactured article. The prior state of the art, and the conditions to be overcome, as well as the means devised for doing so,- are thus described by the inventors in the specifications:

■ “Heretofore in the manufacture of such prism-glass it has been the most approved practice to press the prism-surfaces in molds in the' same manner in which glass articles are ordinarily pressed, a gathering of glass being placed in the mold and the plunger being brought down upon it, so as to displace it anil to cause it to flow into all portions of the mold-cavity and to assume the contour and configuration thereof. It has been found that in this method of manufacture it is not practicable to make prism plates or pieces of large size, and they generally have been made of not more than three or four inches square. The reason of this is the difficulty of causing the glass to flow in the mold while cool enough to prevent burning of the sharp projecting portions of the forming-surface of the latter. Moreover, owing to the means of manufacture employed the prism-plate when pressed, even of .such small size, lacks strength and is apt to be broken. It cannot be cut with a diamond, for when the surface is scored by the cutting-tool it will crack and break upon irregular lines. These practical difficulties have limited' the utility of such glass-prism surfaces, for making of the pieces in small sizes increases the difficulty of assembling them, and the frame in which they are assembled is expensive to make and is more or less unsightly and to some extent excludes the light. Attempts to make prism projections by making the prism-pattern on the sheet-forming roll or on the table of the rolling-machine have been unsatisfactory, so far as we are aware, on account of the difficulty in forming a deep prism-pattern by such operation. We have discovered that all these difficulties heretofore experienced can be avoided and gla^s-prism surfaces made by our improved apparatus in single pieces of large area without impaired strength and capable of being cut with a diamond or other cutting device either parallel with or at an angle to the line of the prisms. Thus instead of forming the glass as heretofore by a single operation of pressing in a mold or rolling oh a table we employ a mechanism comprising in combination two main parts, namely, a rolling-table on which we first roll out the glass into a flat mass and a vertically-moving upper die which may be of the dimensions required for the glass sheet and is shaped on the under side to produce the required prism-pattern. While the flat mass of glass is still plastic this die is brought down upon the surface of the glass, displacing the glass upwardly into the crevices of the pattern, with every portion of which the material is forced into contact until formed to prismatic ridges of glass having sharp angles, finished faces, and clean-cut outlines. In order to produce finished surfaces, the die must be brought against the glass with sufficient pressure to force the glass into contact with the mold over the entire surface thereof. In other words.- the glass must be forced against the whole surface, of the pattern under pressure.”

Distinguishing the method from others which had gone, before,, it is further said that it—

“Comprises two steps, namely, producing a substantially flat sheet of glass and then forming prisms on the ‘surface of the sheet by pressure exerted in a direction transverse to the plane of the sheet upon the entire cross section of the portion to be ribbed. In this operation portions of the' previously-rolled mass of glass while still plastic are simultaneously, over the entire area covered by the die, caught and confined between and in contact with the adjacent ribs by which the prisms are molded, and being thus segregated and confined are compelled to Bow upward between the ribs, so as to form raised prism-shaped ridges or apices, and! this, systematically done over the surface of the sheet, constitutes, as we believe, one of the important features of novelty and utility. By this method two important results are secured. First, inherent molecular straining of the glass is prevented, because in the preliminary spreading the glass is so hot and plastic that it flows freely and in the second step of the operation there is "a Slight uniform vertical motion of the glass particles, but no substantial lateral spreading thereof, and, second, definitely shaped and polished surfaces are secured by bringing the polished surfaces of [357]*357the figuring-die into intimate contact with the material of the glass over the entire cross-section of the ribbed portion.”

“Our improved apparatus,” say the inventors, “is distinct from'' all prior machines in the use of a forming or molding die which does not operate merely to cut into the surface, but which acts to mold the upper body of the previously-rolled mass of glass, so as to destroy what would otherwise be a level surface and impart to the body of the material different transverse sectional form.”

This fairly represents the existing stale of the prism glass art at the time the inventions in suit were projected into it, and the advance upon it which was thereby made. According to the Heidt (1890) patent for instance, for the molding of prism tiles, the glass in a plastic state was pressed by a plunger upon a die or mold, by which- prisnS ridges were formed upon its surface. The prisms nas made were of fairly sharp outline. But the operation being single, and the glass having not only to be displaced vertically into the angles of the die, in order to make the prisms, but also having to spread laterally, in order to reach the edges of the mold, the tiles so formed were not only of necessarily limited size, but the glass, of which they were made, was subj ected to such internal molecular strain that it was very much weakened and could not be successfully cut or scored. A number of tiles, also, having to be assembled together and set in a metal frame in order to make up the required area for a window, not only did this add to the cost, but the ra)rs of light, none too many, were materially obstructed, and a place furthermore afforded for the lodgment of dirt and dust, which, particularly in a place like Pittsburg, detracted seriously from the commercial acceptance and efficiency of the article.

The same objections do not obtain with regard to the rolled prism plate, but there were others which were encountered. By the method of making this, found in the Cummings patent (British 1898) — with which the Walsh (1869) the Stevens (1870) and the Botighton (1880), also all British, are to be classed — the glass in plastic state was poured onto a table having longitudinal V-shaped grooves, and a roller was passed over it, or the table might be flat and the roller grooved. The glass in this way could be spread to any desired extent, without structural distortion, but the difficulty was in securing sharpness and accuracy of outline, as well as depth or prominence of the prisms.

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Bluebook (online)
150 F. 355, 1907 U.S. App. LEXIS 4932, Counsel Stack Legal Research, https://law.counselstack.com/opinion/pressed-prism-plate-glass-co-v-continuous-glass-press-co-circtwdpa-1907.