2 6 4 D O C . 3 1 7 F E B R U A R Y 1 9 2 0 t = universal time parameter: the clock that indicates t is regulated in such a way that one always obtains the value for the velocity of light in any one Galilean frame of reference. The local “mother clock” is then . In general, however, the mother clock itself is a function of the velocities and the coordinates. The law of areas, for ex., is simply written . Another thing. Did you notice that the expression, page 62,[9] is impossible for the velocity of light? The latter should rather be derived from a “velocity ellipsoid.” E.g., at the point , the equation for these ellip- soids reads:[10] Finally, I also point out to you that Mr. Weyl confuses “periods” with “frequency” (Space – Time – Matter, p. 197).[11] In pleasant anticipation of soon seeing you again, I remain with amicable greet- ings, yours, E. Guillaume My wife sends you her best regards. When you come to Bern sometime, she will do a portrait of you. 317. To Konrad Haenisch Berlin, 6a Pariser Place, 19 February 1920 To the Minister of Sciences, Arts, and Education, c/o Senior Executive Officer Helfritz,[1] At the present time, there are approximately 200 young foreigners studying in Berlin from Russia, Poland, Bulgaria, Rumania, and Lithuania, mostly Eastern c0 300,000 = c c0 1 α r --- –= x1------- dx1 dt - x2------- dx1 dt - – const. c × = γ dx1 dx4⎠ -------⎞ - ⎝ ⎛ 2 dx2 dx4⎠ -------⎞ - ⎝ ⎛ 2 dx dx4⎠ -------⎞-3 ⎝ ⎛ 2 + + = P x r, 0 0) , = ( cx 2 c0⎜ 2 1 α⎞ ---⎟ – 1 α ν⎠ ---⎟ + ------------⎟-r ⎝ ⎜ ⎜ ⎛ ------------------------ cy 2 c0⎝ 2⎛ 1 α⎞ r ---⎠ – ----------------------- cz 2 c0⎝ 2⎛ 1 α ---⎠⎞r – ----------------------- + + 1 =