Evening star. [volume] (Washington, D.C.) 1854-1972, 1896-05-30
RIBBED WINDOW GLASS.

Twice as Much Light Comes Through
as Through the Ordinary Pane.
From Casters Magazine.
The advs ntages and disadvantages aris-
Ing from the substitution Of ribbed glass
for plain glass in factory windows were
recently investigated for the Boston Manu-
facturerS Mutual Fire Insurance Com
pany by Mr.. Charles l.. Norton of the
Massachusetts, Institute Of Technology.
Mr.. Merton points cut that in both fair and
cloudy wea Their the general resultant direc-
ton of light entering through a window
having ordinary glass is downward at an
angle Of about forty or fifty degrees. The
brightest portion of the room is, there
fore. the floor In front Of the window. AS
floor Is rot, as rule, a good rejecting
surface, large amount Of light Is alb
sorbed there and lost. Whatever light Is
reflected ( oes upward and backward to-
ward the ceiling, and what light falls on
the wall spaces between the windows
must, there fore. be mainly light which is
dinusely reflected from the floor and OBJ
jects upon it. Early in the morning and
toward evening the angle of the incident
light with the horizontal is less, and the
light, therefore, penetrates further into
the room; but the wall spaces between
windows gain but little by this greater OBJ
liquity. If panes Of ribbed glass be substi-
tuted for the plain glass. the bright spot
pears. and the entire floor walls and cell
irS appear Of sensibly the same brilllancy
The action of the ribbed glass appears 10
be prismatic. the greater part of the light
falling on the ribbed glass at any point be-
Ing refracted and spread out into a fan
shaped beam lying in plane nearly per-
pc molecular to the plane OF the glass and to
the direction of the ribs.
1t has been found that the effect of hav-
ing the ribs horizontal Is to give an In
crease Of light at the middle hole and a
less increase at the sides, whereas the YER
t1cal ribs give a greater increase at the
sides and less increase at the middle
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, useless to discuss
the measure ments of the distribution with
horizontal ribs the brlliancy of the
glass itself is then so great as to be I'M
bearable. 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 rib
bed glass was used. and objects near the
window were cooler than wnen plain glass
degrees Fahrenheit. However the ribbed
glass itself Is hotter than the plain glass;
and the temperature of the air in the two
cases was I Ut sensibly different.
Ht " HiuO"S Oh 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 i'm
preston of almost unimpaired daylight
No window shades are required, and the
results have proved wholly satisfactory
In two Instances rooms iE factories which
are overshadowed by neighboring buildings
are now being fitted with this glass, and it
has been len arked tfat the rela tive in
crease IN the effectiveness of light Is much
greater where the light is derived Indirect
ly than where 1t is derived directly from
the sun tC which the viii GCws are exposed.
1t has been suggested that manufacturers
might test this matter at very small eX-
pense, selecting or core windows in
especially dark places for the purpose of
observing the effect. A very large new
establishment near Boston is row being
glazed in this way. The effect Is already
manifest from a partial Applicant of the
theory. The working men and women in
this establishment are OF a very high type;
hence the foreman reasoned that objection
might be taken to the complete closing of
the outlook from the factory by the use of
this glass throughout the window. The
windows in this factory are of the ordi-
nary lifting type; therefore the lower
panes have been glazed with plain or clear
glass while all the rest of the window Is
glazed with the ribbed glass. The effect Of
this Is said to be entirely satisfactory and
pleasant