Cornell's Making of America collection has scans of this periodical from 1878-1901.
jhutch has downloaded all of these scans, prepped many of them, and they are gradually working their way through the system.
The Uberproject thread on the Forum (with considerable style guidance)
Current status of all 244 projects is available via project search.
Also See Periodicals_Guide/American_Missionary for further generalised proofing, formatting & PPing advice