I have no idea regarding the source of this illustration, which measures 4¼ inches by 5¾ inches. It was printed on very thin paper and does not appear to be cut from a magazine. One guess is that it might have been a tipped-in plate from a book.
It's an interesting illustration, though. What game do you think these three boys are playing? Hide-and-seek? Capture the flag?
Or perhaps these are some boys who are on summer vacation from Hogwarts School of Witchcraft and Wizardry, and are — in violation of school rules — preparing to use their wands for some playful magic. (Those sticks look too thick to be wands, but it's a fun thought nonetheless.)
Here is a closer look at the boys...