Re: See the New Tether! and re: Orientation Format

Jim Varney (
Fri, 16 Aug 1996 22:32:41 -0700

Walter wrote:

>> >sp could be count of sparkles 

I'm a little unclear on the definition of a "sparkle."
How does it differ, if it all, from FFF or ssm?

>> Vertex angle is usually not measured from the apparent vertical. 
>I don't know this.  Do you have a reference? 

Oops, my error.  I was thinking of p.a. and celestial north.

Now that you've convinced me that there won't be any confusion over
the definition of 'vertex angle,' I think the v.a. system is fine.
Just to be sure I have this correct: 20 deg LML = 20 deg v.a. and
20 deg LMF = 160 deg v.a.  ...right?

>>In the engineering world the term for deviation from vertical is "slope." 
>The engineers I know about have been taught that slope is the "m" 
>coefficient in y = mx + b.  Which is not measured in degrees. 

m is the algebraic slope of a line, yes.  The slope I was referring to
is the inverse of 'grade,' i.e., a railroad grade of 10 percent can
also be thought of as having a slope of 5.7 degrees.  Common practice
is also to measure slopes as run:rise, as in 2:1 slope... er, time to
get on-topic again :)

>Is there some (desirable) way the observer could be given a choice?  I'm 
>trying to make it easy for the observer to get it right. 

Maybe quote both systems until we get used to v.a., as in "170 v.a.(10 LMF)"?

Jim Varney
Sacramento, CA

      "Newton was the greatest genius that ever existed, and the most
       fortunate, for we cannot find more than once a system of the
       world to establish."      Lagrange.