332 
OBITUARY. 
are here estimating the quantity of air necessary to destroy the light by burning the 
solid carbonaceous particles, and therefore we should experiment on the gas burning at 
a given rate—say, 0-84 cubic foot per hour. The instrument thus gives reliable indica¬ 
tions of the quality of the gas, as may be seen from this diagram, which is taken from 
the experiments of Mr. William King, of Liverpool. 
Illuminating Power of Gas when burned at a given Rate in Erdmann's Gas Prover — 
viz., at 0 - 84 Rate Cubic Foot per Hour. 
Description of Gas. 
Equal Parts, 
Newcastle 
Newcastle 
Wigan 
Boghead 
Coal. 
and Wigan. 
Coal. 
Coal. 
Height of flame (inch) . 
1-87 
2-00 
2-75 
5-50 
No. of index of prover . 
4-72 
23-39 
32-78 
61-14 
Relative values of do. 
1-00 
1-59 
2-22 
4-15 
Coefficient of power . . 
0-70 
0-70 
0-72 
0-70 
Illuminating power (co- 
cfficient=0 - 7) . . . 
10-30 
16-37 
22-95 
42-80 
Do. do. by photometer . 
10-30 
16-35 
23-58 
42-96 
Relative values . . . 
1-00 
1-58 
2-29 
4-17 
The general laws which have been deduced from these facts are—1. That with all 
burners the maximum amount of light, in the case of common gas, is always secured by 
burning the gas at a pressure of from 0'8 to 0T2 of an inch of water at the orifices of 
ignition. 2. That with Argand burners of 15 holes the best size is the (TOG of an inch 
for each hole, and with 30 holes the measurement should be the 0‘024 of an inch ; and 
with fish-tails or union burners, the holes should be the 0-06 of an inch, and the slit of 
the ; bat’s-wing the 0 - 03 of an inch wide. 4. That the consumption of gas should be 
regulated in the Argand to a little below the top of the chimney, and in the fish-tail and 
bat’s-wing it should not range beyond from 3J to 4} feet per hour. 4. As the measure¬ 
ment of the burner has much to do with the supply of air to the gas, the external dia¬ 
meter of an Argand burner with 15 holes and a 7-inch chimney should be IT inch, and 
the internal diameter 044 inch; while in the 30-hole burner and 8-inch chimney 
(Bengel), the external diameter should be 0*89 of an inch, and internal diameter 0 - 35 
of an inch; and the diameter of the nipple of the fish-tail or bat’s-wing should range 
from 0 - 22 of an inch to 0'35. 
These are the leading facts to be kept in view; and now, in conclusion, I have to say 
that there yet remain many important points for consideration, not only as regards the 
combustion of gas for economic purposes, but also as regards the chemistry of the waste 
products, as they are called, in the manufacture of gas; and these I hope to have an op¬ 
portunity of elucidating. 
Dr. Letheby was ably assisted in his lecture by Mr. Sugg, who provided all the instru¬ 
ments and burners used during the lecture. 
©tituarg. 
DR. LINDLEY. 
The following particulars of the life and writings of our late eminent Honorary 
Member is abstracted from a notice in the ‘ Athenaeum ’:— 
“Dr. Lindley was born at Catton, Norfolk, in 1799, and at an early age turned his 
attention to the study of the Vegetable Kingdom. 
“ Dr. Lindley’s external history is briefly told. He was for many years Secretary to, 
not to say the life and soul of, the Horticultural Society during its palmiest days, when 
botanic collectors such as Douglas and Hartweg were sent out to remote parts of the 
world, when Knight and Sabine published the results of their investigations, and new 
methods of cultivation were practically and successfully demonstrated at Chiswick. To 
his connexion with this body of enlightened men is owing his conception of his ‘ Theory 
