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
    or...
       
    Reply
    Re: Comments on the units
    From: Jean-Philippe Planas
    Date: 2006 Apr 7, 11:37 -0700
    The French artillery (and infantry) uses division called "thousandth" (milli?me") as well. "One Thousandth" is the angle of an object one meter high seen from a 1000m (1 km distance) with the same conclusions as Alex.
    JPP

    Alexandre E Eremenko <eremenko{at}MATH.PURDUE.EDU> wrote:
    Perhaps this does not fit exactly in
    the list scope but I will comment a bit about this funny subject
    of the units.

    On Fri, 7 Apr 2006, George Huxtable wrote:

    > | We think of the metric system being firmly established in the world, but
    > | only a part of it -- measurement of distance and temperature -- is
    > | universal.

    I am surprised with this statement.
    If you subtract the US, from the rest of the world,
    the metric system if firmly established in EVERYTHING
    except time/angular measures.

    Of course there is nothing good or natural about base 10 at all.
    Bases 8 and 12 are much more convenient for many purposes.
    I know of one attempt of transfer to base 8
    (Charles XII of Sweden tried to introduce it as a general standard.
    But he died young (and defeated)).

    > Grads (100, not 90, to the right-angle) still appear on some French maps.

    In Soviet artillery, at least when I served for a brief period in 1975,
    the angle measurement unit was called simply "one division".
    There were 6000 divisions in the full circle.
    The reason for this was that 6 is a reasonable approximation to 2pi.
    Thus an object of size 1 meter is seen at the distance of 1 kilometer
    under the angle of 1 division, approximately.
    So if you see a tank whose height is 3 meters under the angle
    of 2 divisions, the distance is (3/2) times 1000=1500 meters,
    very simple for quick calculation in your head:-)
    But the precision instruments were also graded in "divisions"
    to avoid confusion.

    Confusion however occured in the interaction with
    our aviation where the angles were naturally measured in degrees...
    or with the navy where the distances were measured in cables
    and miles but the angles still in degrees:-)

    Grades were also used somewhere in the military but I don't remember
    where:-)

    But speaking seriously, probably one reason why the system based
    on 60 still holds is that 6 is close to 2pi. Closer than 10 anyway:-)

    Is there anything similar to the Soviet "division" in the West?

    Alex.



    JPP


    Love cheap thrills? Enjoy PC-to-Phone calls to 30+ countries for just 2?/min with Yahoo! Messenger with Voice.
       
    Reply
    Browse Files

    Drop Files

    NavList

    What is NavList?

    Join NavList

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

    You can also join by posting. Your first on-topic post automatically makes you a member.

    Posting Code

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

    Email Settings

    Posting 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