Subject: Re: 49th Parallel FunFacts<br/>
Date: Nov 27, 2001 @ 00:58<br/>
Author: bjbutler@bjbsoftware.com (bjbutler@...)<br/>
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<div id="ygrps-yiv-170523072">Interesting thought, but no reason to think the variance would be<br/>
sinusoidal if it&#39;s due to gravitational anomalies.  It would be<br/>
proportional to the square root of the distance (including elevation)<br/>
from the higher/lower density object embedded in the crust.  And<br/>
congratulations, you have provided the first opportunity to use my<br/>
degree in geology since I got it 26 years ago!<br/>
<br/>
<blockquote><span title="qreply"> --- In BoundaryPoint@y..., &quot;Brendan Whyte&quot; &lt;brwhyte@h...&gt; wrote:<br/>
&gt; Jones, &quot;Boundary-making&quot;, Carnegie endowment, 1945.<br/>
&gt; fig.24 on p154 maps pillars 46 to 58. The bundary is the &#39;mean<br/>
astronomic <br/>
&gt; parallel&#39;. it does not coincide with the geodetically determined<br/>
49th due to <br/>
&gt; the effect of gravitational anomalies on the levelling of instruments.<br/>
&gt; If someone has a list of lats and longs for the pillars, why not<br/>
convert the <br/>
&gt; dms to decimals, and plot them all in Excel as a graph. Then we can<br/>
see how <br/>
&gt; sinusoidal the pillars are compared to the 49th itself.<br/>
&gt; Perhaps someone can develop a fourier series to describe the path of<br/>
the <br/>
&gt; boundary joining the pillars which must be rather wave-like?<br/>
&gt; <br/>
&gt; BW<br/>
&gt; <br/>
&gt; <br/>
&gt; &gt;Any opinion as to why Monument 490 is as accurate as it is with<br/>
respect to <br/>
&gt; &gt;latitude?  I assume that monumentation of the 49th is as varied as<br/>
it is <br/>
&gt; &gt;due to the limitations of older astronomical surveys, etc.  Since<br/>
&quot;once <br/>
&gt; &gt;it&#39;s marked, it&#39;s marked&quot; is the general rule, is fair to conclude<br/>
that <br/>
&gt; &gt;#490 was surveyed much more recently than most of the other monuments?<br/>
&gt; &gt;<br/>
&gt; &gt;Bill<br/>
&gt; &gt;<br/>
&gt; <br/>
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