for centuries, with all the accuracy needed for navigation, for
determining time or for approximate boundaries of countries. The
investigations now in progress at the greatest observatories have
little, if any, value in dollars and cents. They appeal, however, to the
far higher sense, the desire of the intellectual human being to
determine the laws of nature, the construction of the material universe,
and the properties of the heavenly bodies of which those known to exist
far outnumber those that can be seen.

Three great advances have been made in astronomy. First, the invention
of the telescope, with which we commonly associate the name of Galileo,
from the wonderful results he obtained with it. At that time there was
practically no science in America, and for more than two centuries we
failed to add materially to this invention. Half a century ago the
genius of the members of one family, Alvan Clark and his two sons,
placed America in the front rank not only in the construction, but in
the possession, of the largest and most perfect telescopes ever made. It
is not easy to secure the world's record in any subject. The Clarks
constructed successively, the 18-inch lens for Chicago, the 26-inch for
Washington, the 30-inch for Pulkowa, the 36-inch for Lick and the
40-inch for Yerkes. Each in turn was the largest yet made, and each time
the Clarks were called upon to surpass the world's record, which they
themselves had already established. Have we at length reached the limit
in size? If we include reflectors, no, since we have mirrors of 60
inches aperture at Mt. Wilson and Cambridge, and a still larger one of
100 inches has been undertaken. It is more than doubtful, however,
whether a further increase in size is a great advantage. Much more
depends on other conditions, especially those of climate, the kind of
work to be done and, more than all, the man behind the gun. The case is
not unlike that of a battleship. Would a ship a thousand feet long