D O C U M E N T 4 9 0 M A Y 1 9 2 5 4 8 5
490. To Karl Glitscher
Bilbao, 27 May 1925
Dear Dr. Glitscher,
I was on a lecture tour in South America and am now on the return journey. Over
there, one finds more well-tailored clothes than fine and interesting fellows inside
them. It still is better and more interesting at home in Europe—despite the political
and other European madness.
Yesterday a gentleman boarded the ship whom I had seen in Kiel last year and
who is interested in the mining
gyroscope.[1]
He told me that the problems with the
mirror were solved, but not the ones with the suspension. He also told me that you
now want to try it out with the floating sphere. Because in my opinion the optical
difficulties are very considerable in this case, I would like to propose to you an op-
tion which you might not already have considered.
The gyroscope is hung on a socket
joint, whereby the socket’s vertical
axis is made to perform exactly sym-
metrically forced rapid (compared to
the period of oscillation) oscillations
around the vertical. This consequent-
ly involves a dynamic elimination of
bearing friction.
[2] forced rotary oscillations
[3] mirror
[4] gyroscope
I believe that one can attain freedom from systematic disturbances in this way
better than by the use of a suspension wire. I prefer not to make any suggestions
about the manner in which the rotary oscillations are most conveniently generated
and with the best symmetry, as all of you can judge that better.
With best regards to Mr. Anschütz—if he is there—, to Mr.
Richter,[5]
to your
family, and to Mr.
Otto,[6]
yours,
A. Einstein.
[2]
[3]
[4]