D O C U M E N T S 4 4 3 , 4 4 4 F E B R U A R Y 1 9 2 5 4 3 7
We thank you in the name of the cause for the attention you would kindly devote
to this request.
Very sincerely yours,
Hans Kohn.
443. From Heike Kamerlingh Onnes
Leyden, 24 February 1925
Dear Friend,
It pleased me very much that you found occasion, after all, to persuade Lorentz
not to spend 11 Dec. in
America.[1]
I was just about to ask Zeeman and
Fokker[2]
by interlocal telephone for authority to urge Lorentz, also in the name of all his in-
timate friends, to be here on 11 Dec. when your message to
Ehrenfest[3]
arrived
and, at the same time, a letter from Lorentz to me, which removed all worries. Cor-
dial thanks! Now I may surely also remind you of one point on the agenda: to send
me the precise name of Mr. von Siemens so that I can ask Planck and
Laue[4]
to
invite this gentleman.
With cordial regards, your faithfully most devoted
H. Kamerlingh Onnes
444. To Theodor Kaluza
[Berlin,] 27 February 1925
Esteemed Colleague,
I am of the opinion now as before that your idea to construct a link between grav-
itation and electricity is of great originality and deserves the serious attention of our
fellow
professionals.[1]
It constitutes, alongside the Weyl-Eddington idea, the sole
attempt in this direction to be taken seriously. It would be desirable that you soon
find the time and leisure to devote yourself to these problems
again.[2]
I myself have been grappling with this problem entirely in vain up to now. It of-
ten seems to me that the Earth’s magnetic field is based on a still unknown connec-
tion between gravitation and electromagnetism; but I cannot find my way out of the
inconsistencies. Perhaps you will manage with your method.
With best regards, yours,
A. Einstein.