Medium-large format young persons magazine. I have a couple of volumes. [At moment can only find one, vol 6, 1901]
1917-1950 are available on CW.
At least 16 volumes published.
Many articles from the magazine available on STEM.
Sidney Thomson was editor together with Hughes from 1964-1976 then alone in 1976-1989, see vol. 1990, page 145 and page 241; see also page 25 (death of Hughes). The magazine was also issued in 1990 because Thomson left enough papers but it was finished then.