12 
Newcomen, an ironmonger at Dartmouth, associated himself 
with Cawley, a plumber of the same place, and they together 
carefully investigated the phenomena of atmospheric pressure, 
and the formation of a vacuum by the agency of steam ; and 
Newcomen certainly transformed an imperfect, and for many 
purposes a useless machine, into a really efficient steam engine, 
which could be applied profitably and safely to the most 
important uses. Newcomen should share a pedestal by the side 
of Watt ; the ingenious contrivances of the obscure ironmonger 
of Dartmouth, the result of minute observation, have had 
much to do with the advance of civilization. 
Of the inventions of Watt it is scarcely necessary to speak; 
the fertility of his genius is known to all ; and the history of his 
progress informs us that every advance made by James Watt 
was a comment on the text I have chosen, — the value of 
observation. Of the importance of the inventions of James 
Watt well may Arago, in his Eloge, speak as follows : 
“We have long been in the habit of talking of the ago of 
Augustus and of the age of Louis XIV. Eminent individuals 
amongst us have likewise held that we might with propriety 
speak of the ago of Voltaire, Rousseau, and Montesquieu. I do 
not hesitate to declare my conviction, that when the immense 
services already rendered by the steam-engine shall be added to 
all the marvels it holds out to promise, a grateful population 
will then familiarly talk of the ages of Papin and of Watt.” 
Heat, as a force or principle, most intimately connects itself 
with the steam engine, and we are hence led on to a considera- 
tion of some ot the phenomena which are associated with calorific 
action. Water at the level of the sea boils at 2 1 2° of Fahrenheit 
when under ordinary conditions. The minute observations of a 
Belgian engineer have led to the discovery that when water 
freed from air is exposed to heat, ebullition does not commence 
until it arrives at a much higher temperature, and that then it 
occurs with almost explosive violence. lie has also proved that 
if water in this state is brought to the temperature of 250° or 
260 , and then a single drop of water containing air be allowed 
to fall into it, that the whole volume becomes agitated in a 
terrific manner, that indeed an explosion occurs. 
