D O C S . 1 8 1 , 1 8 2 N O V E M B E R 1 9 1 9 1 5 5 Are you thinking of writing a supplement to your book on relativity (Vieweg col- lection) in the near future?[8] I remember clearly what a good reception this book had in Vienna after its publication, and the thought has often occurred to me to translate the book. There was little probability, though, of it being published at that time in the English language but now that the war is over and we can look ahead to better times, it has become relevant. I would very much like to hear what you say to the question of a possible translation, which I would very much like to take on. Any suggestions you may have about this poss. project would interest me as well. A popular book about these subjects is very much needed over here and I am con- vinced of the good reception such a book would encounter here. In begging your pardon once more for troubling you with this letter, I sign with sincere respect, Robert W. Lawson. 181. To Wilhelm Hort [Berlin,] 29 November 1919 Esteemed Colleague, Unfortunately, demonstrating dynamic fields of gravitation by experiments in the laboratory is practically excluded because of the weakness of those fields.[1] The reason for this is that the factor k enters into all those formulas in order of mag- nitude .[2] Numerical calculation of such problems takes a form very similar to that in the electrodynamics of quasi-stationary currents, because the field equa- tions to first approximation can be approximated by linear ones. You will find the method in the enclosed paper.[3] Even the dynamic gravitational fields generated by the rotation of the Earth and Sun, for which we have the Moon or the inner planets, resp., as sensitive indicators, remain below the limit of observation.[4] With great respect. 182. From Arnold Berliner Berlin, 29 November 1919 Virtually nothing but Einstein is being talked about here, and if he were to come over now, I think he would be celebrated like a victorious general. The fact that a German’s theory was confirmed with observations by the English has, as is daily becoming more evident, brought the chance of collaboration between these 10 27–