A sample single issue cover can be seen here https://www.amazon.com/Herald-Salvation-Illustrated-Magazine-Literature/dp/B003WM9X60/ref=olp_product_details?_encoding=UTF8&me=
There is an announcement in The Christian Week, Volume 2 (ie 1880)
"First published in 1878, The Herald of Salvation was originally edited by R. J. Hopkins. In 1893, when Alex Marshall returned from Canada, Mr. Pickering asked him to undertake its editorship, and from that time until Mr. Marshall's decease in 1928, The Herald was his favorite project Its present circulation is 27,000 copies per month." L.o.I. 1952.