9 8 D O C U M E N T 8 0 M A R C H 1 9 2 2 will sit himself down and write to a friend: “It was worth the effort to have taken a look at this poor, rich, strange, and ordinary world.” Who knows, maybe it comes from his will to live that I’ve been thinking for a while already that, since you are currently actually in contact with all sorts of indus- tries, you might perhaps be able to . . . ease my decision to finally let go of the pat- ent application with the enclosed content. The basic idea is that the local intermeshing of textile fibers, which is produced by friction in the spun fibers inside each fiber and by the fabric weave, is achieved by chemical treatment and by as localized a fusing of the fibers as possible. Thus with a minimum of work, struc- tures similar to felt are supposed to form, but distortable and washable. The most nearly similar industrial products are 3)[3] hat felts, for which the suction process described in the patent description is already being applied 1) the veil of crossed fibers of artificial silk, which are made to stick together prior to strengthening 2) and parchmented papers, for which, however, the softening and gluing together of the fibers is not as carefully localized as I plan to have it.[4] If you should happen to know someone who could be interested in this, I would thank you very much, in the name of my grandchild. Or perhaps not—for who knows, maybe the family soul will need to be fortified again by a frugal diet. As for mine, it is uncomfortably soft. I was in Trieste for two days and found my mother unusually well. Then the grandchild arrived here with a punctuality that was of mutual benefit to the health of mother & child. I should calm down and finally be able to do a little work for the office again, but every flutter stops me, everything revs me up (or perhaps better said, down). The stupid scribbling by poor Guillaume, for example,[5] which I makes me ashamed that I can’t find the final persuasive word at least for a third-party listener respectively it actually also con- cerns Lorentz, purely logically speaking: Namely, local time is introduced without any clear definition. Thus perhaps G[uillaume] thinks he may also play around at will with the Lorentz transf[ormations]. But . . . not to find at will, etc. On this occasion I happily chanced upon the properties of the “graphic trajectory” of two- dimensional kinematics, which permits such a clear discussion of the various the- ories of light and for reproduces the Lorentz transformation by the simplest of projective relations (polar line of the sy and polar plane). Has this form of repre- sentation already been properly employed and anywhere? In Weyl it has been sketched correctly, of course,[6] but only for the Lorentz transformation, whereas it is nice to follow Ritz’s other theories of light on the same picture and it is also nice to expl give the derivation of the Lorentz transformation and the Lorentz con- traction with its help, or, resp. using this diagram as explanation.—