1 2 2 D O C . 1 4 5 O C T O B E R 1 9 1 9 they, rather all fields of knowledge. Assyriology, for ex., is about the miscreations of idle brains. What the intrepid researchers decipher as text is in actuality only— chaff! Strindberg entitles the chapter “Mesopotamian Chaff” and proves that the scribble-scrabble is only the chaff that the Assyrians mixed into their brickstones before baking them.—In physics you can learn much, e.g., that X rays can also be generated with a kerosene lamp, which physicists don’t do, however, because it costs too little money!– For you, dear Elsa, I enclose a little book that also falls within the realm of art. I love it as the testimony of an earnestly struggling artistic soul.—How are your daughters?[6] So, now I want to crawl into bed and read Busch I often find there a fine echo of my heretical soul![7] Good night, dear people! Yours, Hedi Born. 21 October 1919 I attach another joke I made yesterday at our house in honor of Landé’s Habilita- tion. A sideshow to the Becker letter.[8] Please return Wertheimer’s letter ev[entually].[9] 145. From Max von Laue Würzburg, 40 Mergentheimer St., 18 October 1919 Dear Einstein, I would like to ask you for advice about a scientific problem. For 6 years now I have been agonizing over the outcome of an experiment by Harress at the Jena Observatory, conducted under the direction of O. Knopf, on the optics of moving bodies.[1] The author set a large glass object of about 20-cm radi- us in rotation, let a ray of light pass through its periphery (approximately) in the direction of rotation, another in the opposite direction, and then from the interfer- ence between the two rays inferred an influence on the velocity of light by the motion of the glass. His result, according to his opinion, absolutely did not agree with the Fresnel dragging coefficient. I want to tell you right away that I succeeded in detecting Harress’s basic error in his theory. Upon correction, one arrives at a quite fair result. According to Prof. Knopf’s reworking (Harress became a victim of the war), which is appearing immi- nently in the Annalen, one finds 0.570 from Harress’s experiment as the dragging coefficient, whereas the theoretical value would be 0.595.[2] Nevertheless, this out- come is not all that secure. Harress had, due to faulty theory, completely failed to