in his experiments led to a corresponding
change along all similar parts of the crystal. The angles, the edges,
the faces, were modified in the same way, at the same time. All these
elements of mensuration within the crystal Hauey thought could be
indicated by rational coefficients.

{181}

Crystallography, however, did not absorb all Hauey's attention. He
further demonstrated his intellectual power by following out other
important lines of investigation that had been suggested by his study
of crystals. It is to him more than to any other, for instance, that
is due the first steps in our knowledge of pyro-(or thermo-)
electricity. Mr. George Chrystal, professor of mathematics at the
University of St. Andrews, in the article on electricity written for
the ninth edition of the Encyclopedia, says it was reserved for the
Abbe Hauey in his Treatise on Mineralogy to throw a clear light on this
curious branch of the science of electricity.

To those who are familiar with the history of the development of this
science it will be no surprise to find a clergyman playing a prominent
role in its development. During the days of the beginning of
electricity many ecclesiastics seem to have been particularly
interested in the curious ways of electrical phenomena, and as a
consequence they are the original discoverers of some of the most
important early advances. Not long before this, Professor Gordon, a
Scotch Benedictine monk who was teaching at the University of Erfurt,
constructed the first practical electrical machine. Kleist, who is one
of the three men to whom is attributed the discovery of the principle
of storing and concentrating electricity, and who invented the Leyden
Jar, which was named after the town where it was first manufactured,
was also a member of a Religious Order. As {182} we have already
stated, Dirwisch, the Premonstratensian monk, set up a
lightning-conductor by which he obtained sparks from the clouds even
before our own Franklin.

Abbe Hauey was only following a very common precedent, then, when he
succeeded by his original research in setting the science of
pyro-electricity firmly on its feet. It is true, others before him had
noted that substances like tourmaline possessed electrical properties.
There is even some good reason for thinking that the _lyncurium_ of
the ancients which, according to certain of the Greek philosophers,
especially Theophrastus, who seems to have made a close study of the
sub