Evening star., 1932-07-24


tute "stove" in heating its
charming patio where 100
species Of tropical plants are grown as mtrl-
guing ornamentals.
True to say, the miracle of growing these
tropicals outdoors in the latitude of Washing
ton during Winter weather has thus far evaded
consummation. However, the "Pan-Am' ex-
perts are raising these hot-climate plants in
doors without artificial heat and with nothing
more than thin panes of glass IN portable
skylight' separting the tender growing things
from National Capital Winter frigidity.
The strange arrangement IS such that during
the coolest days in Washington when the mer-
curry ranges from to 10 degrees above zero
the temperature in the PanAmerican Building
patio never falls lower than 10 degrees despite
that neither radiators, hot-water pipes, heat
ing coils nor other artificial sources OF IN
creased indoor temperature are employed.
Tropical plants demand direct sunlight ex-
posure, fresh air and heat If they are to live
and mature to the glory Of complete floral
magniicance in a foreign and cold latitude
Approaching these facts, the Pan American
authorities equipped their patio with NAM
moth "skylight on wheels" operated by electri-
city which can be thrown open during favor
able sunshiny days to let the weather in and
which even during the dead of Winter aids in
heating the indoor garden" by solar radiation
through the thin but strong glass.
This movable roof, the only one OF its kind IN
current use, is the successful product OF re-
search and experimentation. 1t has been re-
modelled since its first experimental days and
now works we'll anything mechanical
made of steel and glass and functioned by
electricity the sleeping power giant, could pos
sibly work.
When you understand that this gargantuan
skylight weighs 14k tons-it is composed Of
tons of steel and 6l2 tons Of Glasgow will
better appreciate that engineering mechanical
wizardry necessarily had to be invoked in its
practical construction and operation. Any one
familiar with building construction under
stands the difficulty associated with building q
permanent skylight so feet square which would
be waterproof. To make a movable contrap-
ton of that size and weight was much more
difficult.
A S originally built after much study and re-
search, an elevator lift installed NJ one
end of the sliding skylight was used to operate
it by means of series of whips or idlers. This
arrangement required some very long y inch
cables the slack and stretch of which caused
the roof to move unevenly This resulted in
the occasional breaking of both cables and
glass. It caused undue strain on both the
walls and roof. The skylight on wheels de-
veloped the habit of staging such a breakdown
when weather conditions were such that it
was most needed for daily service.
That led to the eventual perfection by H.
Burkholder, superintendent Of the Pan -Ameri-
can Union Building, of a new style of auto
matte operation for the movable roof over the
patio. Ultimately, Mr.. Burkholder installed .
220-volt 5horSepower motor in the basement of
the building as the practical giant designed
to slide the 141a ton skylight back and forth
as desired. This motor moves the skylight by
means of worm and bevel gears ON a shaft
extending from the basement to the roof of
the building On top of the building, a second
shaft has been provided which extends cross
wise to parallel shafts connected to worm and
pinion gears that are meshed into geared
rack fastened to the movable skylight. The
movable section of roof is equipped with roller
bearing wheels, which double f1anged to
prevent them from jumping the track of heavy
railroad rails on which they run. The housings
containing the worm and pinion gears are
fastened securely to the base supporting this
track, while the weight of the vertical shaft
leading from the basement to the roof is car
ried by special roller thrust bearing made
expressly for that purpose
During hot weather, this skylight can be
opened fully. exposing area of the patio
5Ox50 feet In floor dimension to the bright sun
light. This automatic "ventilator' in addition
to exposing the tropical plants to fresh air
and sunshine without moving them outdoors
also provides for the entrance of plenty of
fresh air, which results In a delightful modi-
f1cation of the temperature conditions inside
the building.
The mighty skylight can be opened by the
electrical control in exactly IA minutes. This
derous weight which must be moved without
breakdown or tenn Neither uo,,f1er uor voi<o