NavList:

If you've ever taken a sight with a sextant, done the sight reduction and then plotted a Line of Position (LOP) on a chart you ought to have my latest book: "Line of Position Navigation, Sumner and Saint-Hilaire, The Two Pillars of Modern Celestial Navigation."

The book is about the history of the development of the LOP method of finding a position on a chart. The story starts with Sumner's brilliant concept of "circles of equal illumination" in 1837; continues with Marcq Saint-Hilaire's contribution in the 1870's of using estimated positions to determine intercepts; and ends with a description of the refinements of the technique in the twentieth century.

Key features are a complete reprint of the first edition of Sumner's book of 1843 and the translation of two of Saint-Hilaire's publications from the original French. As you can see, it is not just another "how-to" book but a historical treatise drawn from the original material.

To find out more about the book and how to obtain your copy, go to http://home.fuse.net/pwifland .