Books with the same extended title, Mensuration Made Perfectly Easy, By the Assistance of a New-Improved Sliding-Rule; ..., and printed in Birmingham, England, but with authors, printers, and sellers other than Samuel Davis, appeared as early as 1762 and as late as 1819, according to WorldCat records. WorldCat reports books printed by "C. Earl, No. 50, Dale End" only during the 1770s (as of June 2018). However, based on the appearance and language of the book, its owner, Tom Wyman (1927-2014), who owned a large collection of early books about the slide rule and its use, judged it to date from the early 1700s. Vincenzo Scamozzi (c. 1550-1616) was a Venetian architect. Samuel Davis ... is a mystery.
The Preface to the book and the start of Chapter I are shown below.
Source: Oughtred Society, Archive of Collections, Tom Wyman Collection. Tom Wyman (1927-2014) was the first president of the Oughtred Society. Wyman assembled an extensive collection of early slide rules and books related to them. The images above are photos 2-4 in Item #413 in the Wyman Collection.
Index to Mathematical Treasures