A Balanced Prism Canopy or Daylight Reflector for Windows.
Year: 1897

page_text: Date of Application, 13th July, 1897-Accepted, 28th Aug., 1897
COMPLETE SPECIFICATION.
A Balanced Prism Canopy or Daylight Reflector for Windows.
I, JOHN MEIGGS EWEN, of No. 1129 The Rookery, Chicago, County of Cook,
State of Illinois, United States of America, Mechanical Engineer, do hereby
declare the nature of my invention and in what manner the same is to be per-
formed, to be particularly described and ascertained in and by the following
statement —
My invention relates to a device for adjustably holding prism canopies. These
prism canopies consist of comparatively heavy prism lights assembled together to
form a prism plate, and this prism plate is intended to be mounted outside the
In the ordinary
window or aperture through which the light is to be introduced.
use of such a canopy it is evident that it must be moved in and out, or in other
words, folded against the window or projected therefrom. Moreover it is very
desirable that it be so constructed and mounted that it can be readily adjusted
from time to time to vary its inclination, and thus control to a degree its action.
It is also highly desirable that such a prism plate should be so mounted that
when in actual use for introducing light it will leave a space at the upper part
of the window for ventilation. Since in many instances the prism plate is pre-
ferably of substantially the same length as the window, it will be seen that this
necessitates mounting the prism plate in such a way as to cause the upper end of
the prism plate to descend when the plate is extended. There are other features
in a construction of this general nature highly important to be accomplished,
and they will be hereinafter more fully referred to.
My device is illustrated in the accompanying drawings, wherein
Figure 1 is an elevation of a prism plâte mounted and in a substantially vertical
position;
Figure 2 is a similar view, the plate being inclined;
Figure 3 is a cross-section, the parts being shown in substantially the relation
of Fig 2.
Figure 4 is a detail of the pivotal supporting part;
Figure 5, the same from a different point of view;
Figure 6, an elevation of this with other associated parts;
Figure 7, a detail of the lower supporting parts;
Figure 8, a detail of the arm connection.
Figures 9 and 10, details of the lower rail and eye for controlling the device.
Like parts are indicated by the same letter in all the figures. A A are the
surrounding portions of the window frame. B is a prism plate associated there-
with preferably as nearly as possible of substantially the same width as the window
openings. This prism plate is associated with two arms C C, one on each side,
each pivoted at the point D to the window frame and also pivoted at a point E
to the side bar F of the prism plate B. The side bars F F of the prism plate
are joined at G to the cross-bar H, which together with the side bars and the
lower end bar form the frame of the prism plate. The cross-bar H is turned over
at J and pivoted at K by the anti-friction rollers in the channel bars L. The
distance from the pivot point K to the pivot point E is equal to the distance

page_text: from E to D, and each of these distances is substantialiy equal to one-fourth of
the entire length of the prism plate. N is the lower frame piece of the
prism plate. The pivot points or rollers K K are adapted to roll
up and down in the channel bars L so that the frame at that end is pivoted
but on a movable pivot. These channel bars are held in position on the frame
and in proper relation to each other by the screws M M, being shaped as indicated
in Figure 6, so that the bent portion J of the top bar H passes between the two
portions of such channel bars. Since the pivot point D is fixed and the pivot
points K K are movable, it is evident that the prism plate B may be inclined more
or less; and since the distances from the pivot E to the pivots K and D are the
same, the centre of gravity or the middle point of the plate B will move back and
forth in a horizontal line; or in other words the prism plate is so supported that
its centre of gravity when it is swung to different inclinations travels
on a horizontal line, and therefore there is the least possible friction on the
parts, the plate will stay in any desired position, and the plate can be minutely
adjusted. At the lower end of the plate and on the cross-bar N is secured the eye
piece whereby the plate can be drawn in or out. Since the upper end of the
prism plate is free to move in a vertical line, it will, when extended as shown in
Figure 3, leave a space at the upper part of the window for ventilation.
i
1++
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 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 Figure 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
atriking against the various parts of the window. A prism plate of this character re-
quires 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.

page_text: Having now particularly described and ascertained the nature of the said inven-
tion and in what manner the same is to be performed, I declare that what I
claim is:-
1. A plate supported at its upper end by vertically moving pivots in combina-
tion 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.
2 A movable prism canopy substantially as shown and described.
Dated this 13th day of July 1897.
For the Applicant,
W. LLOYD WISE,
46 Lincoln's Inn Fields, London, W.C., Chartered Patent Agent.