NavList:

Edward J Willis was an interesting fellow. have searched this forum's archives and have not found any discussion about him. He was born in 1866 and died in 1941. His father was a lieutenant in the old USN and later a captain in the Confederate States navy. He was dishonourably discharged along with certain other Southern officers whose resignations were not accepted.

Willis wrote two books on navigation - in 1921 and 1925 - and constructed and patented a navigating machine.

Willis claims to have devised a superior CN method using differential calculus rather than spherical trigonometry. However his method appears to use the standard spherical trigonometry equations. He recommends using Crelle's tables but will accept the use of Martelli. The differential part of his method is the calculation of latitude and longitude corrections (which he calls differentials) to calculate position.  This is exactly what Cloudy Weather Johnson had done nearly 50 years earlier.

Willis did not like the haversine formula - see Methods of Navigation p 17.

I have a problem with his writing style, particularly his 1921 book  - dense text with few paragraphs or sub headings. 19th century texts are sometimes difficult to read because algebra is avoided but I would prefer to try and read a 19th century text than Willis!

Bowditch 1958 devoted several pages to Willis' method.

I am having difficulty understanding Willis' method. Has anyone studied Willis?  Can they provide a fully worked example using Willis' method? If so it will save me lots of work!

=========== Links to relevant documents follow ==============

1921 The Mathematics of Navigation

https://archive.org/details/mathematicsnavi00willgoog/page/n7/mode/1up

1925 The Methods of Modern Navigation

On hathitrust. Cannot download pdf and must use Hathitrust viewer.  (My sister is a librarian and she will try and get her library to become a hathitrust partner).

https://hdl.handle.net/2027/mdp.39015038721869

Copies of the book are for sale on Abe books.

Patent

https://patents.google.com/patent/US2064236

Willis navigating Machine

catalogs.marinersmuseum.org...Willis Navigating Machine
[Mangled link repaired --FER]