Peckston’s Theory and Practice of Gas-lighting. 459 
retorts have undergone such improvements in point both of the 
facility and the ceconomy of working them, that though not used 
at Mr. P.’s establishment, they are now used almost everywhere 
else—at the Royal Mint, Bristol, Birmingham, Chester, &c. 
While we have thus pointed out some of tbe deficiencies which 
have arisen from the circumstance of Mr. P. confining himself too 
much to his own experience, we must not forget a tribute of well- 
deserved praise, which remains to be paid to the various Tables 
which he has given of the results of that experience. They are 
all very accurate, and calculated to be of great value to practical 
men. 
The following is Mr. P’s table of contents :-— 
Chap. 1. Theory of the production of artificial light, and of 
the action of candles and lamps; with directions for ascertaining 
the illuminating power of candles, lamps, and Gas-lights; and 
for computing the relative cost or value of light emitted by each. 
—Chap. 11. On a method for increasing the light afforded by 
tallow candles, for obviating the necessity of snuffing them, and 
for rendering them more fit substitutes for candles made of wax. 
—Chap. III. On the natural history of coal and its component 
parts, as ascertained by analysis—Chap. IV. On the economy 
of using pit-coal as fuel—the heat it generates—the forms of 
grates and fire-piaces—with remarks on the various abuses prac- 
tised in the coal trade, &c.—Chap. V. The theory of the com- 
bustion of coal considered for the purpose of explaining the nature 
of gas light and its production.—Chap. VI. An historical state- 
ment of the successive discoveries which have been made in de- 
composing coal—and on the rise and progress of coal-gas being 
applied as a substitute for the light afforded by burning wax, tal- 
low, or oil.—Chap. VII. On the retorts, and the best mode of 
setting them.—Chap. VIII. On carbonization, as far as relates 
to the most beneficial time for working the retorts, and the per- 
centage at which it may be carried on.—Chap. IX. On the Hy- 
draulic main and dip pipes. —Chap. X. On the condensing main, 
and various methods of condensation.—Chap. XI, On the situ- 
ation and construction of vessels for receiving the tar and ammo- 
niacal liquor, with the description of a contrivance for showing 
the exact quantity of each product from a given quantity of coal. 
—Chap. XII. On the purifying vessels, and the best mode of 
purifying coal-gas.—Chap. XIII. On the gas-holder (Gasome- 
ter) ; its construction, and descriptions of such as would best an- 
swer the purpose of the manufacturer.—Chap. XIV. On various 
kinds of valves, syphons, and tar-wells.—Chap. XV. On the 
laying down of main-pipes in the streets—the arrangement of 
diameters, and remarks thereon.—Chap. XVI. On the service- 
pipes, and fittings up, with the sizes and description of burn- 
ers 
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