376 
Mr Gordon’s New Portable Gas Lamp, 
Description of the Figures in Plate IX. 
Fig. 1. is one of the Portable Gas Lamps, 6 inches in diameter 
and 9 inches high, exclusive of the hemispherical ends and 
burner at the top. When filled with coal gas condensed 25 
times, it will supply a lamp equal to 5 candles, 6 to the pound, 
for 6 hours; and when filled with oil gas, it will burn for 
about l2 hours. 
Fig. 2. is a sphere of 12 inches diameter, and filled aS l^ig. 1. will, 
with two argand burners, equal to 12 candles, burn for up- 
wards of 6 hours with coal gas, and 12 hours with oil gas. 
Fig. 3. contains a cylinder 6 inches dianieter and 2 feet high, 
exclusive of the hemispherical ends, and is calculated to sup- 
ply an argand burner, equal to 10 candles, for 6 hours with 
coal gas, and for 12 hours with oil gas. 
N» B. Although gas made from oil burns longer than that 
made from coal, yet it is doubtful if the great difference 
mentioned above does not arise principally from using 
burners pierced with smaller holes. 
Fig. 4. is the reservoir of condensed gas, for supplying lamps 
with facility. At A, where the gas is to be allowed to issue 
from the condensed reservoir, the valve is placed. B is the 
finger-screw to raise the valve. C the perforated male screw, 
upon which the lamp is to be screwed. 
Fig. 5. is the stop-cock, which is constructed as already descrL 
bed. 
Fig. 6. is the set of brass, already described, to be screwed on 
when a valve is used. 
Art. XXVI. — Notice of the Progress of Botanical Science 
in Bengal, being the substance of a Letter from Dr Wal- 
LiCH, Superintendant of the Botanical Garden near Calcutta, 
to Francis Hamilton, M. D. F. B. S. & F. A. S. L. & E. 
Soon after Dr Wallich’s appointment to the Botanical Garden 
near Calcutta, he obtained the permission of Government, and the 
sanction of the Honourable E. Gardner, Resident at Kathmandu, 
