Thomas Dyche (17403), A new general English dictionary, (London). It's to be found at www.archive.org. Here's the title page of the 3rd edition:
Next a sample page, which shows, among other words, the stress pattern for forthcoming.
We don't know much about Dyche; there is, however, an interesting article on Dyche (and his co-author Pardon) written by D.T. Starnes and G.E. Noyes: "Thomas Dyche and William Pardon's A New English Dictionary (1735)" to be found in R.R.K. Hartmann, ed. (2003), Lexicography, vol. 2, pp. 15-28 (London, New York).