A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
From: David C
Date: 2020 Sep 26, 19:10 -0700
I wonder if I have found yet another way of solving the navigational triangle? While looking at the list of pdfs I had downloaded I came across one called
The Mathematics of Navigation E J Willis 1921
Because I had ssumed that it was just another navigation text I had not looked at it. When I glanced at it today I realised that it is of more interest than a standard navigation text. The author believes that the navigational triangle should be solved by plane trigonometry and differental calculus. He seems to be anti-logs. The only tables needed are natural trigs and Crelles and a 20" slide rule. Martelli seems acceptable. Here is how he begins in a discission about the haversine method:
In order to "simplify"(?) they usually make use of the fact that haversine X =...............
Crelles tables can be downloaded at
I do not know if Willis' method works or how easy it is to use. I do not understand it. My interest has been in locating a copy of Crelles tables which I had not heard of before. I have searched the navlist archives and did not get a hit for Crelle. The only paper copy I could find was a 21st century reprint on demand . I am posting this method so that the method is searchable.
 Is it possible to remove on demand reprints from book searches?