What a marvellous first post and a wonderful opportunity for this book to be reunited with a descendant of Samuel - how thoughtful of you.
There was certainly both a Samuel Carson and a Samuel Carson Jnr in the townland of Procklis (the closest sounding/looking to Rockless, which was not a townland name), in Drummaul parish at the time of the Griffiths Valuation, which would fit with the timescale of the book.
Having done some research on other names in the Parish, I shall certainly see if I can help shed some light on any possible descendants and am sure other members reading this will be happy to do likewise.
And indeed, as you say, in another post, Dixie Dee has noted the following:
Birth:
Josiah Carson, born 13 May 1875, Prockliss, Drummaul, Co Antrim.
Parents, Samuel Carson, a farmer, and Elizabeth boyd.a
I also have details of an 1888 directory for the area, and a Sl. Carson is noted at Procklis as is a J Carson.