D O C U M E N T 8 8 N O V E M B E R 1 9 2 7 9 1 88. From Georg Count von Arco Berlin SWII, Hallesches Ufer 12–13, 15 November 1927 Dear Professor, For image transmission, we have developed a synchronized setup containing a motor that is fed without corrections and without energy transmission, that is, a mo- tor fed directly from a local current source that has an enormous stability.[1] The latter is, when the temperature varies by no more than 1°, about 106, and with spe- cial precautions with respect to the temperature, it could be increased to 107. One can naturally connect a simple counter to such a motor and thereby obtain a clock that is considerably more accurate than astronomical clocks. My question to you now is if such a clock would be suitable for determining whether the rotational pe- riod of the Earth’s axis is constant. The current that feeds the synchronous motor is controlled by a tuning fork that is connected to a cathode ray tube and is part of a feedback loop. This is the only component of the setup that could be influenced by the gravitational field. It appears, however, perhaps to be possible to reduce the in- fluence of gravity to a vanishingly small value by adding a corresponding fixture. I would be very grateful to hear your opinion on whether you believe that such a clock would be sufficiently independent, and whether it would then be of interest to science. With best wishes, yours very sincerely, Arco