, and that from Hansen himself.

To be revised, pulled to pieces, or superseded, as science advances,
is the common fate of most astronomical work, even the best.
It does not follow that it has been done in vain; if good, it
forms a foundation on which others will build. But not every great
investigator can look on with philosophic calm when he sees his work
thus treated, and Hansen was among the last who could. Under these
circumstances, it was a serious question what sort of reception Hansen
would accord to a reviser of his conclusions who should venture to
approach him. I determined to assume an attitude that would show
no consciousness of offense, and was quite successful. Our meeting
was not attended by any explosion; I gave him the pleasant message
with which I was charged from his daughter, and, a few days later,
sat by his side at a dinner of the German commission on the coming
transit of Venus.

As Hansen was Germany's greatest master in mathematical astronomy,
so was the venerable Argelander in the observational side of the
science. He was of the same age as the newly crowned Emperor,
and the two were playmates at the time Germany was being overrun
by the armies of Napoleon. He was held in love and respect by the
entire generation of young astronomers, both Germans and foreigners,
many of whom were proud to have had him as their preceptor. Among
these was Dr. B. A. Gould, who frequently related a story of the
astronomer's wit. When with him as a student, Gould was beardless,
but had a good head of hair. Returning some years later, he had
become bald, but had made up for it by having a full, long beard.
He entered Argelander's study unannounced. At first the astronomer
did not recognize him.

"Do you not know me, Herr Professor?"

The astronomer looked more closely. "Mine Gott! It is Gould mit
his hair struck through!"

Argelander was more than any one else the founder of that branch of
his science which treats of variable stars. His methods have been
followed by his successors to the present time. It was his policy
to make the best use he could of the instruments at his disposal,
rather than to invent new ones that might prove of doubtful utility.
The results of his work seem to justify this policy.

We passed the last month of the winter in Berlin waiting for the
war to close, so that we could visit Paris. Poor France had at
length to succumb, and in the latter part of March, we took al