Having just used the book the last June, I think what you are asking is the dates of the entries.There are two parts to the book.One listing the person owning land and some cenus work (1830,1840,1850) on that person then the plat with the date of recorded purchase plus the code for the plat (T20 R14 S20).The maps of the plats is another section showing the location of the plat. Each plat map having the code T# R# on the front with a copy of the County map for that section of the county then a second map with the breakdown of the plots with the S# on it and the name of the owner. From what I have seen concerning my own folk, the entries go from as early as 1830 to as late as 1850. It is a terrific book and I wish each county had one. Sorry if this doesn't make sense.