Figure 1. G. F. Barker. Copyright © Mark I. Grossman
Figure 2. Back of Barker Photo. Copyright © Mark I. Grossman
In his talk, Barker showed three vials of radium salts, as well as a radiograph of a mouse, all of which he obtained from W. J. Hammer (1859-1934), author of the 1903 book, Radium and other radioactive substances. Two radiographs of a mouse (one on a plate and the other caught in a trap) are shown in Hammer’s book (pages 38-39), but only one was used by Barker in his Columbia lecture (p. 290). Hammer worked for Thomas Edison, was an early experimenter with radium having obtained samples from Pierre and Marie Curie in 1902, and developed the infamous radium paint used on watch dials.
Figure 3 displays a letter in my collection that was written by Barker to Hammer on March 15, 1903 in preparation for his Columbia lecture just a few days away, and is on University of PA Morgan Laboratory of Physics letterhead. It reads in part:
“Dr. Chandler has asked me to repeat my talk before the Chem. Soc. of Columbia Univ. on Thursday evening (the 19th)… I would like to borrow for that evening your polonium metal & the three most active radium tubes. Also, can you spare me the slide of the mouse (without the trap)?
Barker to Hammer, 3/15/1903. Copyright © Mark I. Grossman
Never mind the radiation concerns. Seems like Barker did not want to disturb his audience with pictures of any dead mice caught in traps!
I am particularly fond of this letter because it not only mentions the radiographs that can be viewed in Hammer's book and Barker's lecture, it references Columbia chemist Charles Frederick Chandler (1836-1925) and the behind-the-scenes preparation for Barker's talk.