"Air baths are good for preventing colds. What you do is strip naked mornings and evenings and then bob up and down for a while.” Golden-Age Feb 1926 pg 310
Yep. I can just imagine it now. Mrs J.F. Rutherford walks into the office of the President of Watch Tower one morning...
Mrs J.F. Rutherford: "Who's she."
Mr J.F. Rutherford: "She's my faithful and discreet servant."
Mrs J.F. Rutherford: "And what is your servant doing bobbing up and down like that?"
Mr J.F. Rutherford: "She's taking an air bath."