2 2 V O L . 7 , D O C . 6 5 a D O C U M E N T 1 (taken at the temperature of the compressor). If there is also cooling between compressor and exchanger, then the total cold developed by the exchanger and evaporator is raised by an amount equal to the removed heat . The degree of efficiency thereby rises by . A more accurate theory must take into account the thermal conduction of the exchanger, as a completely insulated nonconducting exchanger could not have a stationary temperature distribution. Comment: A lower limit for the attainable refrigeration is given in that at the lowest temperature (evaporator) cannot become negative. Vol. 7, 65a. Expert Opinion on Proposal by Heinrich Löwy[1] Berlin, 12 October 1921 Expert Opinion[2] I know about the suggestions by Dr. Heinrich Löwy, Vienna, regarding ground depth analysis through the influence of the ground’s interior on an external oscil- lating electric circuit.[3] In my view this proposal deserves serious examination from the technical angle. From the standpoint of the theory it may be stated that Dr. Löwy’s method rests on solid theoretical bases and that the anticipated effects do lie thoroughly within the range of modern measurement precision. 1. To Charlotte Weigert[1] [Berlin, early 1922][2] Dear Miss Weigert! Elsa has been pestering me dreadfully about giving you a recommendation to Niels Bohr.[3] But I had to resist, I’m sorry. Bohr is the greatest genius in physics today, enormously busy and mentally exhausted for a long while. Now he is K A --- - Tdν νdT -- - ------ 1–= W′ W′ νΔp ---------- T∂ν ν -- - ∂p ----- - 1–