Lorentz and his Monday morning lecture class, around 1910. To the right of Lorentz stand his Ph.D. students Droste, de Haas-Lorentz (also his daughter), and Bruins (front). To his left stand Vollgraff and Bremekamp. (More on this photograph, also here and here).
Titels are linked to a scan of the thesis, names are linked to photographs scanned from the Liber Amicorum for H.G. van de Sande Bakhuyzen (1908).
Read a letter from Lorentz to this astronomer.