Are you acquainted with the Family History Centers of the LDS (Mormon) churches? If not, you simply must make their acquaintance. Look in your phone book for 'Church of Jesus Christ of the Latter Day Saints' and see if one has an extra phone number for the FHC (Family History Center). If so, call that number. If not, call the church and ask how to locate the FHC. If you go to one of these centers, ask them to help you find Agnes Nesmith English's book. I don't recall the order, but it was called 'JOHN BROCKINTON,JOHN NESMITH, AND JOHN MOUSON' - and I think I've misspelled the last one. Anyway, they can find the microfilm that has the book on it, and you can order it for just the cost of postage. When it arrives at the center, you can go there and use their equipment to read the microfilm, and to copy pages you want to keep. It's not the easiest book in the world to follow, but it has a tremendous amount of information on these three families.
I'm descended from the Nesmith and Brockinton families in lots of ways. The most recent marriage was of John Brockinton (the fourth, I think) to Sarah Nesmith, daughter of Samuel Nesmith who was one of the Rev. War heroes. I've worked on these families for about 40 years. The English book is a great place to start. Another - though quite mixed up about the SC Nesmith line - is John W. NesSmith, author of NAESMYTH DESCENDANTS OF GEORGIA, USA. If you look in the wills of South Carolina (extracted and printed in three volumes for years before the Rev. War), you'll find that nearly all of the Brockinton and Nesmith men left wills and they spell out the lineage pretty well.