ELECTRIC LAMPS
Year: 1881

page_text: PROVISIONAL SPECIFICATION left by the said James Grieve Lorrain at the
Office of the Commissioners of Patents on the 31st December 1881.
JAMES GRIEVE LORRAIN of 2 Victoria Mansions Westminster.
IN ELECTRIC LAMPS."
.
"IMPROVEMENTS
My Invention relates to improvements in incandescent and other electric lamps
and has for its objects diffusing the light and economizing the same by preventing
its radiation in directions where its effects are not required and of concentrating
the light in a required direction and also rendering it more pleasant to the eye, and
the Invention consists in silvering or coating with a reflecting material a portion
or portions of the bulb or globe of the lamp in such a manner as to produce the
effects before mentioned.
In the case of incandescent lamps the coating should be applied to the exterior
of the globe or bulb at a suitable part or parts of the same according to the
position which the light is to occupy in the space to be illuminated. The silvering
may be effected in the usual manner. I prefer to cover the silvering or reflecting
coating with a protecting coating of varnish.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed
by the said James Grieve Lorrain in the Great Seal Patent Office on the
30th June 1882.,
JAMES GRIEVE LORRAIN of 2 Victoria Mansions Westminster.
IN ELECTRIC LAMPS."
"IMPROVEMENTS
In incandescent electric lamps as ordinarily constructed a great defect is the
disagreeable effect which the light produces upon the eyes.
The glowing filament of such lamps makes such an impression upon the retina
that the image remains present for a very considerable time after looking at the
lamp and very disagreeable and inconvenient results are produced.
It is an objection to such a light that there is an absence of what may be
termed the "solid sheet" of light presented by a gas flame.
Several methods have been adopted with the view of avoiding this inconvenience
such as frosting the bulbs or enclosing them in an outer frosted globe such methods
however entail a loss of lighting power of 40% or more.
Now my improvements have for their object to remedy these defects and to
avoid this loss.
By silvering or coating with a reflecting material a part of the outside of the
bulb or globe varying from 45° to 60° or more of the circumference of the bulb or
globe according to the position the bulb or globe is to occupy a very good effect is
obtained and the_appearance_of_-a-solid-sheet-of-light-is-then-presented. The
radiation of the light in directions where its effects aro not required is thus
prevented and the rays are reflected in the direction where the light is required.
By this means a very considerable economy is effected. The coating should be
applied to the exterior of the bulb or globe and I find the following to be a good
method of silvering. The silvering of the required part of the bulb or globe may
conveniently be effected by iminersing such part into a solution capable of
precipitating bright silver. Such a solution may be made thus. Procure tartrate
of silver (which may be obtained by precipitation from a solution of silver nitrate
by addition thereto of a solution of rochelle salt) and then dissolving in ammonia.
If this solution be heated to about 66° C. for some minutes bright silver will be
deposited on any part of the glass globe that is immersed in it.
The silvering or reflecting material may be protected by a coating of varnish or
other protecting material caro being taken to employ a varnish which will not be
injured by the heat of the bulb. If the bulb be arranged to hang downwards and
be placed at a considerable height I prefer to silver the whole of what will be
the upper half of the bulb when so hanging downwards and to apply this coating
throughout the entire circumference of such upper half. If the bulb be to occupy.
a position in a lustre I prefer to coat only one side the angle to be covered of
course depending upon the number of bulbs to be placed in the lustre and if the
lustre be placed in an elevated position more or less of the top part of the bulb
should also be silvered. However much of the side of the bulb is to be coated the
part so coated should be behind the plane passing through the two legs of the
filament.
Having now described and particularly ascertained the nature of my said
Invention and the manner in which the same is or may be used or carried into
effect I would observe in conclusion that what I consider to be novel and original
and therefore claim as the Invention secured to me by the hereinbefore in part
recited Letters Patent is.

page_text: The improvement in electric lamps consisting in silvering or coating or covering
a portion of the globe or bulb with a silvering or reflecting material as herein before
described.
In witness whereof I the said James Grieve Lorrain have to this my
Specification set my land and seal this Twenty ninth day of June One
thousand eight hundred and eighty two.
J. G. LORRAIN. (L.S.)