1169 Derek Pilgrim Before GPS part 1 – the Wayfinders
Historical perspective on how navigation was done before electronic navigation
link Page: 19
1229 Derek Pilgrim Before GPS, part 2, The Measurers
Early compasses, logs, sounding lines, and equipment for measuring celestial elevation
link Page: 21
1293 Derek Pilgrim Before GPS, Part 3
Continued series on history of navigation
link Page: 31
1327 Derek Pilgrim Before GPS Part 4
Continuation of series - Radio Aids to Navigation
link Page: 31