Most of the copies of old issues of Unknown I have are of the British edition - and despite the cover, that's what we have here, a 96-page, neatly trimmed magazine instead of the more "pulpy" American 160-page issue, for October 1939. The international sf database is a bit sketchy on these reprints, and has data on very few of them, so it's lucky I have the item on my lap now. As usual with such reprints, the first thing the British publisher, Atlas, did was to drop the features and articles, so we have no editorial or letters; a poem is also dropped, as is the last story, "The Enchanted Weekend" by John MacCormac.
Advertisements here are only on the inside and back covers, so that saves some space. Soon, a circle with "British 6D Edition" would be added to the cover... but with the early issues, Atlas found it easier just to copy the original cover without any changes, and leave it to the newsagent to add a price sticker if necessary. Forty magazines to the pound sterling sounds good value, anyway, compared to five to the the US dollar.
The lead novella here is the 57-page "The Elder Gods" by Don A. Stuart, though on this occasion that was not just editor John W. Campbell Jr's pen-name, Arthur J. Burks was also involved. "Nazun, Lord of Wisdom, led the Elder Gods against the Invisible Ones - but a man, with material hand and sword, was needed. So--" There was room too for four shorter stories: "Dreams May Come" by H. Warner Munn, "A God in a Garden" by Theodore Sturgeon (his nineteenth short story, after starting his career the previous year), "Anything" by Philip St John (Lester del Rey), and "Blue and Silver Brocade" by Dorothy Quick.
The cover here was by Modest Stein who, according to the isfdb, was mainly active between 1912 and 1926, with just this 1939 cover and the November 1942 Astounding later - though pulpartists.com does add three 1945 Doc Savage pieces. The British edition loses some of the interior artwork, but the illustrations by M. Isip for the lead story are all in place.
So, while Astounding Science Fiction set the pace for science fiction in the late thirties, and throughout the forties, it did have this fantasy-oriented sister publication to keep it company on the stands for a while. Unknown ran from March 1939 to the end of 1940 as a monthly magazine, and then went bimonthly until the final issue appeared with an October 1943 cover date, so that the rationed supplies of paper could be devoted to keeping Astounding going. There was a change of title with the October 1941 issue to Unknown Worlds, while the July 1940 issue did away with the normal pulp-style colour illustration on the cover, in favour of more of an illustrated contents page - but more about that in another post. It is still fondly remembered by fantasy fans, as a strong influence on the direction fantasy fiction has taken over the decades.