5 1 0 D O C U M E N T 3 2 9 O C T O B E R 1 9 2 4 329. From Robert A. Millikan [Pasadena,] October 2, 1924 I am writing to ask if you would not like some time to follow the good example set by Dr. Lorentz and Dr. Ehrenfest and spend the months of January, February, and March playing in and about the Norman Bridge Laboratory and the Mount Wil- son Observatory.[1] Your work is of such importance that I should not suggest this at all if I thought there was the slightest danger of its interfering in any way with that work, but I hope that the latter would actually be stimulated rather than other- wise. What we should want you to do would not be to give any courses at all, unless you wished to do so, but merely to be one of the half a hundred men, all intensely interested in the latest developments in physics and astronomy, who inhabit the Norman Bridge Laboratory and the Mount Wilson Observatory, attending our sem- inar as Ehrenfest did, three times a week, talking with the men when their own problems interest you, visiting the Mount Wilson Observatory and seeing the sort of problems upon which they are engaged, and finally, getting into contact with the very large amount of magnetic results which have been accumulated by the Carn- egie Institution in Baur’s laboratory at Washington, and to some extent in our own laboratory where Dr. Barnett is working,[2] all for the sake of stimulating us and in- cidentally yourself toward new generalizations and interpretations of our experi- mental results. The problem which Bowen[3] and myself are engaged upon, and which I talked over with you in Geneva, seems to us at the present of fundamental interest and one which is right along the line of your more recent work. We see no solution of our dilemma unless it be to deny in toto the applicability of the principle of change of mass with speed to our electronic orbits. This denial encounters most serious diffi- culties, and perhaps when you see how we obtain our results you might see some other solution.[4] At any rate, this is only one of dozens of problems here in which I am sure you would be interested. We have a large new laboratory and could give you rooms in which you would be completely undisturbed for your own work. We would agree to keep the report- ers away from you, and let your stay here be solely for the purposes of the progress of physics rather than for publicity purposes of any kind. We should simply ask you to be a “Research Associate of the Mount Wilson Observatory and the Norman Bridge Laboratory of Physics”, such as Lorentz, Ehrenfest, and Michelson[5] have been already.