Welcome to the NavList Message Boards.

NavList:

A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding

Compose Your Message

Message:αβγ
Message:abc
Add Images & Files
    Name or NavList Code:
    Email:
       
    Reply
    Re: What did Horrocks do?
    From: Alexandre Eremenko
    Date: 2023 Apr 2, 20:39 +0000

    Frank,
    
    I read the paper, and it mostly confirms what I wrote before.
    
    1. Horrocks Lunar theory was written in 1638 in a letter to a friend.
    After his death, all his writings were collected as Opera Posthuma, and privately sent to
    Newton, Flamsteed, Wallis and others. Later this was published, and now avaiable on Internet:
    
    
    https://books.google.com/books?hl=en&lr=&id=xVQ_AAAAcAAJ&oi=fnd&pg=PA1&ots=cW8RsSOQB6&sig=pKMPRH4syyb3EPNAQIQ3wIQZNRw#v=onepage&q&f=false
    
    In Latin, of course.
    
    2. He himself considered this Lunar theory his greatest achievement. 
    It was the most precise available
    predictive Lunar theory before Mayer.
    
    3.  Newton saw his first task is deriving this theory from his law of gravitation
    (and mechanics), that is to do what he did to Kepler's laws. He failed.
     
    That is he failed a) to produce a predictive theory more powerful than that of Horrocks,
    and b) in mathematically deducing Horrocks's theory from the law of gravitation. 
    
    Euler also started with Horrocks's theory and
    "found it suggestive in leading to his invention of the method of variation of 
    orbital parameters, so fruitful
    in the celestial mechanics of Lagrange and Laplace."
    
    The 18 page  paper of Wilson which contains all this information, and a 
    readable description of Horrocks's Lunar theory in English
    is available here:
    
    https://journals.sagepub.com/doi/abs/10.1177/002182868701800201?journalCode=jhaa
    
    for $2.50. I downloaded my copy from my university library, so I will not post it here,
    but I can send a copy to the private e-mail address of anyone who will ask, since sharing 
    a library material for research/educational purposes is considered a "fair use", and is permitted.
    
    It is not known exactly how Horrocks derived his theory, and the main purpose of Wilson's paper
    is a discussion of this.
    
    Alex.
    
     
    
    

       
    Reply
    Browse Files

    Drop Files

    NavList

    What is NavList?

    Get a NavList ID Code

    Name:
    (please, no nicknames or handles)
    Email:
    Do you want to receive all group messages by email?
    Yes No

    A NavList ID Code guarantees your identity in NavList posts and allows faster posting of messages.

    Retrieve a NavList ID Code

    Enter the email address associated with your NavList messages. Your NavList code will be emailed to you immediately.
    Email:

    Email Settings

    NavList ID Code:

    Custom Index

    Subject:
    Author:
    Start date: (yyyymm dd)
    End date: (yyyymm dd)

    Visit this site
    Visit this site
    Visit this site
    Visit this site
    Visit this site
    Visit this site