The ad first ran, I think, in the April 1915 issue. I did not find it in the prior 6 months.
It ran at least through June. I have not checked later months yet.
Here is the full page.
(PS These issues have what may be the earliest Langford articles. I will upload some on another thread.)
(PPS I found an article about a HHH in 1908, 1910, and 1894! I will post that too.)
