als
in their fluid state."

The fifth claim was for a rotary engine, and need not be quoted here.

The early efforts of Watt are typical of those of the poor inventor
struggling with insufficient resources to gain recognition and it was
not until he became associated with the wealthy manufacturer, Mattheu
Boulton of Birmingham, that he met with the success upon which his
present fame is based. In partnership with Boulton, the business of the
manufacture and the sale of his engines were highly successful in spite
of vigorous attacks on the validity of his patents.

Though the fourth claim of Watt's patent describes a non-condensing
engine which would require high pressures, his aversion to such practice
was strong. Notwithstanding his entire knowledge of the advantages
through added expansion under high pressure, he continued to use
pressures not above 7 pounds per square inch above the atmosphere. To
overcome such pressures, his boilers were fed through a stand-pipe of
sufficient height to have the column of water offset the pressure within
the boiler. Watt's attitude toward high pressure made his influence felt
long after his patents had expired.

[Illustration: Portion of 9600 Horse-power Installation of Babcock &
Wilcox Boilers and Superheaters, Equipped with Babcock & Wilcox Chain
Grate Stokers at the Blue Island, Ill., Plant of the Public Service Co.
of Northern Illinois. This Company Operates 14,580 Horse Power of
Babcock & Wilcox Boilers and Superheaters in its Various Stations]

In 1782, Watt patented two other features which he had invented as early
as 1769. These were the double acting engine, that is, the use of steam
on both sides of the piston and the use of steam expansively, that is,
the shutting off of steam from the cylinder when the piston had made but
a portion of its stroke, the power for the completion of the stroke
being supplied by the expansive force of the steam already admitted.

He further added a throttle valve for the regulation of steam admission,
invented the automatic governor and the steam indicator, a mercury steam
gauge and a glass water column.

It has been the object of this brief history of the early developments
in the use of steam to cover such developments only through the time of
James Watt. The progress of the steam engine from this time through the
stages of higher pressures, combining of cylinders, the application of
steam vehicles and steamboats, the adding of thi