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586,223 · Basquin · "Adjustable Prism-Canopy" · Page 2
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is free to move in a vertical line, it will, when extended, as shown in
Fig. 3, leave a space at the upper part of the window for ventilation.
There are many localities in which buildings are lighted by artificial light where it is possible to light them by the light from the sky, and this can be done by the use of the prisms; but in so doing under ordinary conditions the result is to close up the windows by the prism-plates, so that while the heat of the light disappears when the lights are extinguished the room is nevertheless put into an unsatisfactory condition by the confinement of the air by a closed window. A prism-canopy like that here illustrated, which moves vertically and also as to its angle of inclination, avoids these difficulties, for it introduces the light, while at the same time permitting a very great degree of air circulation and ventilation.
These prism-plates are made up of prism-lights or small sections of a practically uniform size, usually about four inches square, though the size may be varied. Evidently when they are to be applied to a window a certain amount of difficulty arises from the fact that the prism-lights, having a uniform width, cannot be worked into groups which will exactly fit the windows. They must always be a little less, and the differences in width will vary through a range nearly equal to the width of an individual prism-light. To avoid the difficulties which would result from these conditions, I have devised the form of frame for the prism-light herein illustrated, the top bar being, as it were, separable from the remainder of the frame. This bar having been made of proper size to fit the window, and with its pivot-rollers in the channel-bars on opposite sides, can then be used as a support for the frame, the side bars of the frame being secured thereto midway, so that the prism-plate will hang in the middle of the window
with half of the unoccupied space on each side. The several obstructing
parts of the arms and supporting parts are cut away, as indicated,
for example, in Fig. 8, so as not to interfere with the prisms on the
prism-plate, and the prism-plate is supported on the bars curved at J, as
indicated, so as to throw the body of the prism back or outward from the
window, and thus relieve the inwardly-projecting prisms from the danger
of striking against the various parts of the window. A prism-plate of
this character requires frequent and minute adjustments. Thus when put
in proper position for the sun at a given angle or at a given time of
day or at a given season of the year or with a given degree of exterior
illumination or for a given degree of interior illumination it is quite
obvious that it must be changed in position to give the same result
under varying conditions or a new result under the same conditions.
Thus it is evident at once that there may be an almost infinite number
of variations, every one of which is useful and important.|
These prism-plates are of course very heavy and unwieldy and must be handled by women and children, and hence must be supported so as to be most conveniently controlled. All these necessities and more have been considered in the production of this invention.
A plate supported at its upper end by vertically-moving pivots in combination with supporting-arms which are approximately one-quarter the length of the plate, are pivotally secured at a fixed point below the moving pivot, and are also pivoted to the plate at a distance from its upper end approximately equal to one-quarter of its length.
F. W. PARKER,
C. A. LONGFELLOW.