rd and fourth cylinders,
to the invention of the turbine with its development and the
accompanying development of the reciprocating engine to hold its place,
is one long attribute to the inventive genius of man.

While little is said in the biographies of Watt as to the improvement of
steam boilers, all the evidence indicates that Boulton and Watt
introduced the first "wagon boiler", so called because of its shape. In
1785, Watt took out a number of patents for variations in furnace
construction, many of which contain the basic principles of some of the
modern smoke preventing furnaces. Until the early part of the nineteenth
century, the low steam pressures used caused but little attention to be
given to the form of the boiler operated in connection with the engines
above described. About 1800, Richard Trevithick, in England, and Oliver
Evans, in America, introduced non-condensing, and for that time, high
pressure steam engines. To the initiative of Evans may be attributed the
general use of high pressure steam in the United States, a feature which
for many years distinguished American from European practice. The demand
for light weight and economy of space following the beginning of steam
navigation and the invention of the locomotive required boilers designed
and constructed to withstand heavier pressures and forced the adoption
of the cylindrical form of boiler. There are in use to-day many examples
of every step in the development of steam boilers from the first plain
cylindrical boiler to the most modern type of multi-tubular locomotive
boiler, which stands as the highest type of fire-tube boiler
construction.

The early attempts to utilize water-tube boilers were few. A brief
history of the development of the boilers, in which this principle was
employed, is given in the following chapter. From this history it will
be clearly indicated that the first commercially successful utilization
of water tubes in a steam generator is properly attributed to George H.
Babcock and Stephen Wilcox.

[Illustration: Copyright by Underwood & Underwood

Woolworth Building, New York City, Operating 2454 Horse Power of
Babcock & Wilcox Boilers]

BRIEF HISTORY OF WATER-TUBE BOILERS[1]

As stated in the previous chapter, the first water-tube boiler was built
by John Blakey and was patented by him in 1766. Several tubes
alternately inclined at opposite angles were arranged in the furnaces,
the adjacent tube ends being conn