5 patented the atmospheric
steam-engine by which he is known, and which, as told by Arago, gave
place to the superior invention of Watt.

Arago was an eminent French physicist and astronomer (1786-1853),
who is even better known through his biographies of other great
workers in science. His account of "the fruitful inventions which
will forever connect the name of Watt with the steam-engine" is all
the more valuable for preservation because written while the
steam-engine was still in an early stage of its development. Of its
later improvements and varied uses, numerous descriptions are within
easy reach of all readers.

In physical cabinets we find a good many machines on which industry had
founded great hopes, though the expense of their manufacture or that of
keeping them at work has reduced them to be mere instruments of
demonstration. This would have been the final fate of Newcomen's
machine, in localities at least not rich in combustibles, if Watt's
efforts had not come in to give it an unhoped-for degree of perfection.
This perfection must not be considered as the result of some fortuitous
observation or of a single inspiration of genius; the inventor achieved
it by assiduous labor, by experiments of extreme delicacy and
correctness. One would say that Watt had adopted as his guide that
celebrated maxim of Bacon's: "To write, speak, meditate, or act when we
are not sufficiently provided with _facts_ to stake out our thoughts is
like navigating without a pilot along a coast strewed with dangers or
rushing out on the immense ocean without compass or rudder."

In the collection belonging to the University of Glasgow there was a
little model of a steam-engine by Newcomen that had never worked well.
The professor of physics, Anderson, desired Watt to repair it. In the
hands of this powerful workman the defects of its construction
disappeared; from that time the apparatus was made to work annually
under the inspection of the astonished students. A man of common mind
would have rested satisfied with this success. Watt, on the contrary, as
usual with him, saw cause in it for deep study. His researches were
successively directed to all the points that appeared likely to clear up
the theory of the machine. He ascertained the proportion in which water
dilates in passing from a state of fluidity into that of vapor; the
quantity of water that a certain weight of coal can convert into