nsequently mechanical ventilation by means
of a large fan, run by steam power, was provided. The efficiency of this
system has sometimes been severely tested. On one occasion, during a
scientific lecture, the experimental illustrations of which were on a
large and imposing scale, the learned professor on the platform had the
misfortune to crack an immense glass jar, in which he was exhibiting the
brilliant combustion of phosphorus in oxygen gas. The white fumes of
phosphorous acid floated out into the air, and began to diffuse
themselves through the hall towards the ventilation outlets at the sides
and rear. To one who knew the irritating nature of these fumes it seemed
inevitable that the hall must be emptied of its crowded audience in a
few minutes. Already coughing had begun on the front seats, when Mr.
Hewitt, who was seated on the platform, quickly rose, and pulling a
cord, reversed the currents of ventilation and opened a new outlet into
the street, behind and above the platform. The curling clouds of vapor
paused, wheeled, and retreated, and in another minute the air was
perfectly pure. The lecturer had not even been interrupted. It was a
beautiful and timely "experiment" not on the programme, and, to use the
words of one who was present, "It was just the sort of thing to please
Peter Cooper to the bottom of his soul."

The great hall was dedicated from the beginning to free speech. Peter
Cooper may have overestimated the value of mere talk. As I have already
told, it was his first notion that conversation and discussion were the
chief things required in education. He came to see that study,
instruction, and training were equally essential, but he never
surrendered his faith in free speech; and the great hall was at the
service of all sects, parties, and classes, religious, philosophical,
political, scientific, literary, or philanthropic. It has been the scene
of many memorable meetings and addresses. But nothing in its history has
been more useful and noteworthy than the series of free popular lectures
which were given, as part of the operations of the Cooper Union, within
its walls. These lectures began in 1868, and continued until they were
adopted by the city as part of the general scheme of free lectures which
has been so successful during the last few years. In awarding due praise
to the promoters and managers of this plan, it should not be forgotten
that the Cooper Union inaugurated it, and maintained it fo