D O C U M E N T S 7 , 8 A P R I L 1 9 2 3 1 1
more. From there I have to go to Leyden for two
weeks.[3]
I am very glad that the
trials with the compass came out so satisfactorily. I shall write to the boys about
Lautrach.[4]
It will be grand.
With cordial regards to both of you, yours,
A. Einstein.
P. S. Don’t trouble yourself about the cottage interior. You know that I am an incor-
rigible gypsy, and untidy to boot.
7. To Unknown
Berlin, 9 April 1923
You will find my first paper, in which the equivalence of inertial mass and energy
is demonstrated, in the Annalen der Physik, volume 17, 1905, under the title: “Does
the Inertia of a Body Depend upon Its Energy
Content?”[1]
The notion that it would
have been possible to base this result on chemical considerations is mistaken. If a
material system releases energy externally during a reaction, then one would surely
have to say, sloppily formulated, that the energy “originated from the system’s
mass of materials”; however, from the chemical standpoint one has no argument
whatsoever that supports the claim that through such a process the system’s total
inertial or gravitational mass experiences a diminution…
8. From Hermann Anschütz-Kaempfe
Kiel, 10 April 1923
Dear esteemed Professor Einstein,
It’s superb that you want to come around the 20th of this
month.[1]
The finished
apartment is awaiting you, and I have a whole list of interesting things to ask: con-
verter, artificial horizon, i.e., pilot’s horizon, a new alternating current relay, etc. I
think you are coming just in time for the launch of the new, or I should say, the lat-
est gyrocompass; re. the damping, we aren’t quite in the clear yet; I think the mer-
cury’s surface tension is
detrimental.[2]
I gather from your letter of today that you obviously did not receive my letter
with the apartment floor plan, which I sent to the university in Tokyo; but now I
won’t write to you about that anymore; now it will just have to suit you, no matter