IMPROVEMENTS IN OR APPLICABLE TO LAMPS
Year: 1879

page_text: PROVISIONAL SPECIFICATION left by John Post Lawrence at the Office of
the Commissioners of Patents on the 7th February 1879. A communication
from abroad by Abel Combs, of Philadelphia, in the United States of
America.
JOHN POST LAWRENCE, of St. Mary Axe, in the City of London, Merchant.
"IMPROVEMENTS IN OR APPLICABLE TO LAMPS." [A communication from abroad
by Abel Combs, of Philadelphia, in the United States of America.]
The Invention communicated to me has for its object to provide means whereby
a glass globe, such as is commonly employed to steady the flame of a gas burner,
may be employed as a substitute for a chimney in connection with a lamp burner,
and the Invention consists in the provision and employment of a metallic disc
having a central opening or aperture of about the diameter of a lamp chimney, the
said disc being applied to a common glass globe so as to form a top thereto, the
said globe being fastened on a lamp burner in the same manner as lamp chimnies
are usually fastened.
The metallic disc is applied to the upper opening of the globe, forming a top for
the said globe. This disc is preferably of a concavo-convex forin, but is not necessarily
so, and may be flattened or less dished if so desired.
The said disc is formed with a central opening of or about the diameter of the
top of a lamp chimney. Around the edge of this disc are formed lugs or other
retaining devices, whereby the said disc is kept firmly in position in the said
globe.
The effect of this improvement is that a lamp provided therewith burns quite as
steadily and brightly as does one provided with a chimney.
The metal disc above the flame is not injuriously affected by the heat, as glass in
the same position would be. It serves to heat the air within the globe and thus
cause an ascending current, the heated air passing out at the central opening and
its place being supplied by cold air rushing in, around, and beneath the base of the
globe, and which supplies the required oxygen to support the combustion at the
burner. The ascending current of air forms a sort of atmospheric chimney extending
from the burner to the opening, serving to steady the flame and produce excellent
illumination.
The globe standing around at a considerable distance from the flame of the burner
does not become so highly heated as to expand to any considerable extent, and
hence is not subject to great or sudden contraction. Hence a globe used with these
improvements will never in ordinary use break by expansion or contraction; whereas,
Price 2dl

page_text: as is well known, lamp chimnies are constantly breaking from these causes; herein
constitutes a very great advantage in these improvements over chimnies. Another
advantage is that the globe-does-not-become-smoked so quickly as a chimney and
is much more easily_cleaned,_the_large_opening permitting the easy insertion of a
hand_with_cloth to remove soot or dirt. The disc also serves as a reflector, and by
throwing down the rays of light, which with a chimney unprovided with a shade
-ascend-uninterruptedly, enhances-the-useful_effects_of_the_lamp, particularly_for_
such purposes as reading or sewing, where a concentration rather than a diffusion
of such rays is desired.