the case of the composition of air. This was determined by that
strange genius and recluse, that man of mystery, that disembowelled
intelligence, Henry Cavendish, towards the end of the eighteenth
century. So far as he was concerned the work was admirably done.
He separated all the known ingredients of the air with a precision
altogether remarkable; he even put it upon record that he had some doubt
about the purity of the nitrogen. For more than a hundred years his
determination was repeated by chemists all the world over, his apparatus
was treasured in London, he became, as they used to say, 'classic,' and
always, at every one of the innumerable repetitions of his experiment,
that sly element argon was hiding among the nitrogen (and with a little
helium and traces of other substances, and indeed all the hints
that might have led to the new departures of the twentieth-century
chemistry), and every time it slipped unobserved through the
professorial fingers that repeated his procedure.

Is it any wonder then with this margin of inaccuracy, that up to the
very dawn of the twentieth-century scientific discovery was still rather
a procession of happy accidents than an orderly conquest of nature?

Yet the spirit of seeking was spreading steadily through the world. Even
the schoolmaster could not check it. For the mere handful who grew up to
feel wonder and curiosity about the secrets of nature in the nineteenth
century, there were now, at the beginning of the twentieth, myriads
escaping from the limitations of intellectual routine and the habitual
life, in Europe, in America, North and South, in Japan, in China, and
all about the world.

It was in 1910 that the parents of young Holsten, who was to be called
by a whole generation of scientific men, 'the greatest of European