s of the medieval astronomers in the Royal Library.
If one knew exactly what books he wanted, and had plenty of time
at his disposal, he would find no difficulty in consulting them
in any of the great Continental libraries. But at the time of my
visit, notwithstanding the cordiality with which all the officials,
from Professor Lepsius down, were disposed to second my efforts,
the process of getting any required book was very elaborate.
Although one could obtain a book on the same day he ordered it,
if he went in good time, it was advisable to leave the order the
day before, if possible. When, as in the present case, one book
only suggests another, this a third, and so on, in an endless chain,
the carrying on of an extended research is very tedious.

One feature of the library strongly impressed me with the
comparatively backward state of mathematical science in our own
country. As is usual in the great European libraries, those books
which are most consulted are placed in the general reading-room, where
any one can have access to them, at any moment. It was surprising to
see amongst these books a set of Crelle's "Journal of Mathematics,"
and to find it well worn by constant use. At that time, so far
as I could learn, there were not more than two or three sets of
the Journal in the United States; and these were almost unused.
Even the Library of Congress did not contain a set. There has
been a great change since that time,--a change in which the Johns
Hopkins University took the lead, by inviting Sylvester to this
country, and starting a mathematical school of the highest grade.
Other universities followed its example to such an extent that,
to-day, an American student need not leave his own country to hear
a master in any branch of mathematics.

I believe it was Dr. B. A. Gould who called the Pulkova Observatory
the astronomical capital of the world. This institution was founded
in 1839 by the Emperor Nicholas, on the initiative of his greatest
astronomer. It is situated some twelve miles south of St. Petersburg,
not far from the railway between that city and Berlin, and gets its
name from a peasant village in the neighborhood. From its foundation
it has taken the lead in exact measurements relating to the motion
of the earth and the positions of the principal stars. An important
part of its equipment is an astronomical library, which is perhaps the
most complete in existence. This, added to all its other