Discussion Map makers and topographic engineers.

19thGeorgia

1st Lieutenant
Joined
Apr 4, 2017
A fairly accurate topo map can be made with an alidade and plane table. Did this a few times in my "reenacting career"-

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infomanpa

2nd Lieutenant
Joined
Feb 18, 2017
Location
Pennsylvania
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Lookout Mountain from the porch at Sugar's BBQ on Missionary Ridge.
How would you make a map of what you are seeing?​

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In answer to a private message, "How did they do it?"
The answer was a Civil War GPS in the palm of their hand.



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This modern sighting compass is identical to the ones carried by Civil War soldiers.
Note the flat spots at 3:00 & 9:00 on the case. They allow it to be set on a level surface.

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Notice that the compass is designed to be read in the mirror.
You aim at a point & use the lever visible in the 2:00 position to lock the compass needle in place.
It make it easy to write down the result.

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This is the inclinometer. Note the E on the compass is boxed by the needle indicating 0 degrees.

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Compare the position of the E on the compass face with the position of the pointer in this image.
Notice that the degrees are meant to be read in the mirror.
What this allows you to do is to sight your point & call out the results to a helper who writes them down.

This handy-dandy compass/inclinometer was an essential piece of personal equipment for engineers & artillery officers.

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Fortress Rosecrans outside Murfreesboro TN
The lines with ranges in yards were made using survey instruments.
The intersections of the lines were marked by white poles with little flags on them.
In December 1864 the Washington Artillery went into battery over a mile from Lunette Negley & Battery cruft.
The first round fired by the 20 pound Parrotts struck a caisson.
A rain of accurate fire drove off the CSA artillery before they could fire a shot.
About ten years ago, a cluster of Parrott shells was discovered at that site.
The rain soaked soil had absorbed the impact of the contact fused rounds without setting them off.
An O.E.D. unit from Fort Campbell blew them up in place.

I'd love to see some of your guys demonstrate the use of these instruments. In a way, it reminds of the way that seaborne vessels used triangulation to locate their position using sextants to measure the angles of the sun, moon and planets.
 

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