rful engine "The Rocket." To those curious in the matter, I may
mention that S. Buren's patents are dated 1823, No. 4,874, and 1826, No.
5,350.

From this time on, a continuous series of gas engine patents appear, 20
engines being patented between 1826 and 1860, which is the next date
worthy of particular mention.

In this year, 1860, the famous "Lenoir" engine appeared. The use of high
pressure steam engines had long been common, and Lenoir's engine was
analogous to the high pressure engine, as Buren's was to the condensing
engine. It created a very general interest, and many engines were
constructed and used in France, England, and America; it resembled very
much in external appearance an ordinary high pressure horizontal steam
engine, and it was double acting.

During the following six years, other 20 British patents were granted, and
the gas engine passed from the state of a troublesome toy to a practicable
and widely useful machine.

From 1791 to the end of 1866, in all 46 British patents were granted for
gas engines, and in these patents are to be found the principles upon
which the gas engines of to-day are constructed, many years elapsing
before experience enough was gained to turn the proposals of the older
inventors to practical account.

The most important of these patents are:

No. Year.
Robert Street 1,983 1794 Direct-acting engine.
Samuel Buren 4,874 1823 Vacuum engine.
Samuel Buren 5,350 1826 Vacuum engine.
W.L. Wright 6,525 1833 Direct-acting engine.
Wm. Barnett 7,615 1838 Compression first proposed.
Barsante & Matteucci 1,072 1854 Rack & clutch engine.
Drake 562 1855 Direct-acting engine.
Lenoir 335 1860 D.I. engine, electric ignition.
C.W. Siemens 2,074 1860 Compression, _constant
pressure_.
Hugon 2,902 1860 Platinum ignition.
Millein 1,840 1861 Compression, both constant vol. and
_pressure_.
F.H. Wenham 1,873 1864 Free piston.
Hugon 986 1865 Flame ignition.
Otto and Langen 434 1866 Rack and clutch, flame ignition.

Leaving for the present the history of the gas engine, which brings us to
a stage comparable to the state of the steam engine during the Newcomen's
time, it will be advisable to give some consideration to the principle