The Portland daily press., 1896-05-30
RIBBED WINDOW GLASS.
Twice as Much Light Comes Through as
Through the Ordinary Pane.
(From Casters Magazine. }

~'~~"to~s0
The advantages and disadvantages
arising from the substitution of ribbed
glass for plain glass in factory windows
were recently Investigated for the Boston
Manufacturers Mutual Fire Insurance
Company by Mr.. Charles L. Norton of
the Massachusetts Institute of 1echnolo-
gy. Mr.. Norton points out that in both
fair and cloudy weather the general re.
sultant direction of light entering
through window having ordinary glass
is downward at an angle Of about forty
or fifty degrees. The brightest portion Of
of the window. AS q floor is not, as q
rule, a good rejecting surface, large
amount of light is absorbed there and
lost. Whatever light is reflected goes up
ward and backward toward the ceiling,
and what light falls on the wall spaces
between the windows must, therefore, be
mainly light which is diffusely reflected
from che floor and objects upon it, Early
in the morning and toward evening the
angle of the incident light with the hori-
zontal is less, AMI the light, therefore
penetrates further into the room; but the
wall spaces between windows gain but
little by this greater obiquity. If panes
of ribbed glass be substituted for the
plain glass, the bright spot on the floor
in front Of the window disappears,
and the entire floor, walls, and ceiling
appear of about ths sams brilliancy.
The action of the ribbed glass appears TO
be prismatic, the greater part of the light
falling on the ribbed glass at any point
h,N;x1 ri
shaped beam lying in plane nearly per-
pendicular to the plane of the glass and
to the direction of the ribs.
1t has been found that the effect of hay
ing the ribs horizontal is to give an in
| crease Of light at the middle hole and q
less increase at the sides, whereas the
vertical ribs give greater increase at
the sides and a less increase at the mid
ole. The horizontal ribs tend to throw
the light which would otherwise fall to
the floor straight ahead far into the room
while the vertical ribs spread out the
light on both sides. 1t is, however, uss-
less to discuss the measurements of the
distribution with horizontal ribs, as the
brillianoy of tho glass itself is then SO
great as to be unbearable, rendering its
use in this position out of the question
for most purposes.
The diffusion of heat is much the same
as the diffusion of light. 1t was found
| that there WAS no spot where the heat
| rays from outside streamed directly in
| when ribbed glass was used, and objects
near the window were COOLER than when
plain glass was used by from degrees
| to IS degrees Fahrenheit However. the
| ribbed glass itself is hotter than the plain
glass, and the temperature of the air in
| the two cases was not sensib1y different.
| The windows Of several large factories
| have thus far been fitted up with ribbed
glass, and the effect in each case has
proved startling, each room giving the
| impression of almost unim paired day
| light. NO win1owshades are required.
and the results have proved wholly salts
| factory. In two instances rooms in fac
| torie which are overshadowed by neigh
boring buildings are now being fitted
| with this glass, and it has been remarked
that the relative increase in the effective
| ness of light is much greater where the
light is derived indirectly than where it
is derived directly from the sun to which
the windows are exposed. 1t has been
suggested that manufacturers might
test this matter at very small expense
fselecting one or more windows in espeo.
tally dark places for the purpose of OBJ
Sowing the effect. A very large new es
| adjustment near Boston is now being
glazed in this way. The effect Is alreadv
manifest from partial application of
the theory. The working men and
women in this establishment are of a
very high type; hence tn foreman reas-
oned that objection might be taken to the
complete closing of the outlook from The
factory by the use Of this glass through.
out the window. The windows in This
factory are of the ordinary lighting TYNE
therefore the lower panes have been
glazed with plain or clear glass, while ali
the rest of the window is glazed with the
~ - L.!
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