6 V O L U M E 5 , D O C U M E N T 2 4 2 a
certainly differ from it; a priori it is not clear at all how K should be defined. If one
defines the force on moving bodies by the relation between force and the magni-
tude of motion, it can be shown that
must be true,
just as it also results from your special example.
Thank you very much for your kind invitation to give a talk in Karlsruhe.
However, whenever possible I avoid giving talks before larger audiences.
With great respect, yours very sincerely,
Vol. 5, 242a. To Heinrich Zangger
[Zurich, 1 January 1911]
Dear Mr. Zangger,
Cordial New Year’s greetings to you and your wife! One doesn’t write to a
prolific writer the way you do to me. I carefully rechecked my calculations con-
cerning the viscosity of suspensions but deemed everything in order. I also re-
quested Mr. Hopf to check it over. Who knows whether Perrin didn’t have some
strong swelling of the particles (1.4-fold in diameter). Bredig thinks it very well
possible. He considers it very difficult to make well-defined suspensions.
I believe I found a new kind of influence by a magnetic field on electrons, but
the magnitude of the effect still needs to be calculated. In radiation theory the evil
spirit is constantly leading me around by the nose. Did you eventually get the
Tammann? I looked for you everywhere before your departure but was unable to
track you down.
I hope your stay will do you & your wife a lot of good. With cordial greetings,
Best regards & and greetings from my wife.
Vol. 5, 255a. To Vladimir Varic;ak
Zurich, 24 February 1911
[Not selected for translation.]
K K 1