248 
NATURE 
| Fuly 16, 1885 
the purposes required; and that the first cost and the 
maintenance of the plant employed should be very 
moderate. In public estimation, simplicity is the first 
desideratum ; and hence a simple and direct form of 
illumination has always been preferred to a more compli- 
cated arrangement, even when the latter has been found 
more economical as regards first cost and maintenance, 
and more brilliant in its effects. At the present time, 
however, in addition to these requirements, a purer atmo- 
sphere and a more pleasant temperature in our apart- 
ments are desired, which matters received very little or 
no attention in former days, when people were content 
with a simple dim light, and took little interest in sanitary 
matters. The regenerative gas-burner may be regarded 
as a combined lighting and ventilating apparatus, by the 
employment of which the close oppressive atmosphere, so 
unpleasant at large gatherings, may be entirely avoided. 
In fact, it is the outcome of the demand for cooler and 
purer airin our apartments, combined with light of high 
intensity. 
The lamp has been designed with a view to protect the 
eyesight from the direct action of the source of light, 
without diminishing its power; its construction will be 
understood from the following description :—Four hoods, 
I, 2, 3, 4, of sheet iron or other suitable material, are 
arranged within one another in such a manner that 
the products of combustion travel downward between 
— 
2 and 3, and upward between 3 and 4, while the 
air to be heated for feeding the flame passes up- 
ward between 1 and 2. On the uppermost hood, 4, 
a chimney, 6, is provided, while the hood, 3, is short- 
ened below so as to allow a clear passage for the pro- 
ducts of combustion from the space between 2 and 3, 
to that between 3 and 4, and thus to the chimney. The 
hood, 2, carries at its apex an inwardly projecting outlet, 
5, through which the products of combustion pass away 
as described, first downwards and then upwards, through 
the passages between the three upper hoods, into the 
chimney. The lowest or innermost hood, I, is open, so 
‘that the air may pass upwards between the hoods, 1 and 
2,as indicated by the arrows, to fill the inner space of the 
hood with heated air. The inner surface of this hood 
acts as a reflector, and in its focus are placed one or more 
fishtail burners of the usual type. As soon as the hood, 
2, becomes sufficiently heated, through the action of the 
products of combustion passing between it and 3, the air 
between 1 and 2 will become heated, and, diminishing in 
its specific gravity, will automatically rise and fill the 
upper portion of the cone inside the hood, 1. By this 
arrangement the gas-jets burn within an atmosphere of 
heated air, with which they are consequently permanently 
supplied ; the temperature of the air increasing with that 
of the gas-flames, and the brilliancy of the light increas- 
ing in the same ratio. The action is perfectly automatic, 
for, as the products of combustion pass away through the 
chimney 6, fresh heated air comes in at the same rate 
into the inner space of the hood 1 containing the gas- 
flames, to occupy the space which would otherwise be 
filled with cold air from the atmosphere below. The hot 
air which is supplied from the column of heated air 
formed between the hoods 1 and 2 will, on account of its 
lower specific gravity, always fill the upper space inside 
the hood 1, thus preventing the cold air of the atmo- 
sphere, which is at least three times as heavy, from rising 
inside the hood, 1, above a certain level, even in case of a 
disturbance in the atmosphere of the room. Thus no 
glass partition to exclude the cold air is required. The 
flame reflects its light directly downwards, as also from 
the inner surface of the hood, there being consequently 
an entire absence of shadows. 
The light can be more or less concentrated or diffused, 
as desired, by varying the shape of the hood or reflector 
used. In some cases, where it is required to diffuse the 
light widely, or to diminish the downward radiation of 
heat, a bell-shaped glass, with its apex upwards, and its 
surface curving parabolically in the downward direction, 
may be employed, so as to cause all the rays of light it 
receives either to be refracted or to be reflected hori- 
zontally. If it is only desired to reduce the intensity of 
the downward radiation of heat, clear glass should be 
employed ; if, however, it is also desired to diffuse the 
light, opaque glass is requisite, and the light may be thus 
more or less diffused, as may be required. The glass bell 
is suspended on a wire net of large mesh attached to a 
metal ring below, upon which and upon the netting the 
glass rests, so that, in case of accident, the broken glass 
would not fall below. It allows of free access to the 
flame, and does not form an integral part of the appa- 
ratus, so that its employment will not cause any particular 
trouble or inconvenience. As the intensity of the light 
depends entirely upon the up-current of heated air, the 
hoods may have any shape most suitable for the reflector 
and for the purpose of diffusing the light, provided that 
the height of the column of hot air between the hoods 1 
and 2 be not relatively diminished. 
The following tests of this lamp have been made :—The 
burners or jets removed from the dome were tested with 
the rays horizontal. The consumption of gas was 20 cubic 
feet per hour, and the illuminating power 57°5 candles, or 
2875 candles per cubic foot. They were then placed at 
an elevation of 1 foot 6 inches perpendicularly over a 
plain glass mirror placed at an angle of 45°, and ina line 
with the disk of the photometer. The distance from the 
standard light to the glass reflector was 18 feet 6 inches, 
which, added to the 1 foot 6 inches that the burners were 
placed above the reflector, made together 20 feet, the 
distance at which the light to be tested has to be fixed 
from the standard light in the photometer employed. In 
this case the consumption was again 20 cubic feet per 
hour, and the illuminating power was found to be 55 
candles, or 2°75 candles per cubic foot; so that it would 
appear that there is an absorption by the glass in retlec- 
tion of 4°35 percent. The burners having been fixed in 
the dome reflector, the lamp, thus arranged, was tested 
again as in thelast experiment. The consumption of gas 
was 20°5 cubic feet per hour, and the illuminating power 
62°5 candles, or an average of 3048 candles per cubic 
foot of gas, or 3180 candles per cubic foot if the 4°35 per 
cent. found to be absorbed by the glass are added. The 
difference between 2°875 and 3180 candles, or 0°305 
candle, per cubic foot gives the increase of light due to 
the use of the reflecting cone. After burning for some 
time the lamp was again tested, the consumption of gas 
was found to be reduced to 15°5 cubic feet per hour, and 
the illuminating power to be increased to 115 candles, 
being an average of 7°42 candles per cubic foot; or, 
allowing for loss by absorption, 7°74 candles per cubic 
foot. The difference between this and 3180 candles, 
