You will find an explanation of the various parts
of the picture written in pencil on the back of each respectively.
You had better have it mounted on a piece of cardboard by some one
who is accustomed to mounting photographs; when nicely done it
looks twice as well. It was intended that we should all have been
taken in this picture, but owing to some mismanagement, no notice
was given, so no one was outside at the time. Your remarks about
the aurora borealis of the 12th of October were very interesting
and valuable. We knew that there was an aurora there, but of course
could not tell where it was visible. You little thought that while
you were looking at the vibrations of those beautiful streamers of
red and white light, I was watching sympathetic oscillations of
little steel magnets, which we suspended by silk threads, in the
underground magnetic house that you see the top of in the
foreground of the picture. The magnets were sometimes moving about
so rapidly that I could scarcely read them; and although the aurora
was with you nearly at an end probably about ten o'clock, yet the
magnets did not resume their normal position for nearly twenty-four
hours after.
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