Tea in Pierre Weiss's Laboratory in the Institute of Technology (Eidgenossische Technische Hochschule) Zurich. Front row L-R: Karl F. Herzfeld, Otto Stern, Albert Einstein, Auguste Piccard (Weiss' assistant, later a balloonist), René Fortrat (Weiss' assistant, author of Fortrat diagram - frequency of diatomic molecules as function of rot, qu. Number) ; Rebekka Aleida Biegel. Back row L-R: Catharina Amelia Frankamp, Paul Ehrenfest, Eva Dina Bruins, Gabriel Foëx, and Frithiof (Fred) Wolfers. Foëx and Wolfers were also Weiss' assistants. (Identification from the description of a variant of this photograph, from Emilio Segrè's photographs at the AIP. Further identification, particularly of the women present and the date, from the research of Jacques Dane and Chris Verhoef, supplementing prior analysis by Joanna Behrman, in a 2023 AIP blog posting, and notes made in 1979 by Beat Glaus of the ETH in Zürich.) Prior identifications suggested A.J. Grigorjeff was pictured.