iry.
But apparently the inquiry was of some value, for it led "to some useful
alterations and new modifications in its apparatus and machinery."

Many improvements were being introduced during these years and one of
them in 1816 increased the gaseous product from coal by distilling the
tar which was obtained during the first distillation. In 1816 Clegg
obtained a patent for a horizontal rotating retort; for an apparatus for
purifying coal-gas with "cream of lime"; and for a rotative gas-meter.

Before progressing too far, we must mention the early work of William
Henry. In 1804 he described publicly a method of producing coal-gas.
Besides making experiments on production and utilization of coal-gas for
lighting, he devoted his knowledge of chemistry to the analysis of the
gas. He also made analytical studies of the relative value of wood,
peat, oil, wax, and different kinds of coal for the distillation of gas.
His chemical analyses showed to a considerable extent the properties of
carbureted hydrogen upon which illuminating value depended. The results
of his work were published in various English journals between 1805 and
1825 and they contributed much to the advancement of gas-lighting.

Although Clegg's original gas-meter was complicated and cumbersome, it
proved to be a useful device. In fact, it appears to have been the most
original and beneficial invention occasioned by early gas-lighting.
Later Samuel Crosley greatly improved it, with the result that it was
introduced to a considerable extent; but by no means was it universally
adopted. Another improvement made by Clegg at this time was a device
which maintained the pressure of gas approximately constant regardless
of the pressure in the gasometer or tank. Clegg retired from the service
of the gas company in 1817 after a record of accomplishments which
glorifies his name in the annals of gas-lighting. Murdock is undoubtedly
entitled to the distinction of having been the first person who applied
gas-lighting to large private establishments, but Clegg overcame many
difficulties and was the first to illuminate a whole town by this means.

In London in 1817 over 300,000 cubic feet of coal-gas was being
manufactured daily, an amount sufficient to operate 76,500 Argand
burners yielding 6 candle-power each. Gas-lighting was now exciting
great interest and was firmly established. Westminster Bridge was
lighted by gas in 1813, and the streets of Westminster during the