Martin Baxter wrote:
Martin Baxter wrote:
Gordon wrote:
This is from the Brian Toss rigging book so if you want to cheat,
you can look it up.

If I string a line around the equator (disregarding natural
obstacles) and then decide I want that line 1 foot above the equator
all the way around, how much longer must that line be? Call the
earth's diameter an even 8000 miles.
G


circumference = pi*d

so difference = (pi*(8000+(1/5280))-(pi*8000)miles

=pi/5280 miles

multiply by 5280'/mile and you get pi ft. (3.2459')

do a little simple algebra


all you have to do is expand the first term:

pi*8000 + pi/5280, subtract the second term and you are left with pi/5280

Or, intuitively, since circumference is diameter time pi, to make the
circumference grow by one foot, you must add pi feet to the diameter;
doesn't matter if the diameter is 1 foot or a light-year, you still add
pi feet.

Ooops, just noticed I only increased the elevation by 6", so change that
to 2pi feet. same principle.



Cheers
Martin