Digital technology and distance at the Battle of Gettysburg?

No, but you could easily measure such using a topo map. USGS 1:24000 quads are available on line for free. Measure the horizontal distance between the two points you are interested in and note the elevation at both points. Using subtraction, calculate the elevation difference between the two points. Use the Pythagorean theorem (Google it) to calculate the distance of the line of sight (which will be longer than the horizontal distance between the two points) which is easy as you will have the length of two sides of a right triangle. Old school comes in handy sometimes.
If my father was still alive I'd have asked him to do exactly what you suggest above. An engineer, math was his wheelhouse. I majored in journalism...
 
I believe that I answered your question in the affirmative, explaining that I use Google Earth. That is a digital technology, no?
While I appreciate your answer, no that does not accomplish my goal. My desire is to find a method using digital technology to measure from an exact spot to another spot, in this case from the crest of Bream's Hill along the modern day Black Horse Tavern Road to the marker for the Signal Corps on Little Round Top. I tried dropping a pin on my mobile phone and driving to the next spot, but that did not work. My GPS device does not have the capability, either. I can, and have, measure it on a map but that is less precise than what I want.
 
Mr Picky Pants tells me that line-of-sight may or may not be horizontal, depending.
Regardless per Bob Velke's suggestion I played with Google Earth, and I get the distance between Bream's Hill and LRT as 2.93 miles.
Did not see this post earlier, sorry. I still don't know how the elevation differences might impact the distance but I do appreciate the note.
 
While I appreciate your answer, no that does not accomplish my goal. My desire is to find a method using digital technology to measure from an exact spot to another spot, in this case from the crest of Bream's Hill along the modern day Black Horse Tavern Road to the marker for the Signal Corps on Little Round Top. I tried dropping a pin on my mobile phone and driving to the next spot, but that did not work. My GPS device does not have the capability, either. I can, and have, measure it on a map but that is less precise than what I want.

Oh, I see. I didn't realize that you wanted distance along a road. Google Earth has a "Path" function to do just that. Download Google Earth.
 
Oh, I see. I didn't realize that you wanted distance along a road. Google Earth has a "Path" function to do just that. Download Google Earth.
Line of sight distance, not driving path. I had hoped to drop a pin, go to the next location and drop another to get the true distance between the two spots, including elevation distance. That has not worked. This measurement is part of a larger project, lots of other things to do along with the distance measurement. I appreciate all of your thoughts.
 
I had some fun with this. The top image is a screenshot of Bream's Hill on Google Earth looking east from the corner of the Fairfield Road and Blackhorse Tavern Road. It gives some idea of how Bream's Hill would block the line of sight between the Blackhorse Tavern and Little Round Top. The middle image and bottom image were done using the measuring tool and elevation profile tool on Google Earth Pro which is a free download. (Note that the elevation profile over long distances can appear somewhat distorted) Other graphics were added using Paint.net, another free download.
Bream's Hill.jpg
Line of Sight 1.jpg
Line of Sight 2.jpg
 
I had some fun with this. The top image is a screenshot of Bream's Hill on Google Earth looking east from the corner of the Fairfield Road and Blackhorse Tavern Road. It gives some idea of how Bream's Hill would block the line of sight between the Blackhorse Tavern and Little Round Top. The middle image and bottom image were done using the measuring tool and elevation profile tool on Google Earth Pro which is a free download. (Note that the elevation profile over long distances can appear somewhat distorted) Other graphics were added using Paint.net, another free download.
View attachment 433515View attachment 433516View attachment 433517
Excellent. And as you can see in your elevation profile, if there are some tall trees on the middle elevation (Seminary Ridge) as there is today, you can no longer see LRT from Bream's Hill. Whereas in 1863 the elevation was barren.
 
This is excellent, basically what I could not figure out how to do myself. I'll get the download ASAP.
Thanks for the work you put in and the clear explanation.
 
This is excellent, basically what I could not figure out how to do myself. I'll get the download ASAP.
Thanks for the work you put in and the clear explanation.
This is excellent, basically what I could not figure out how to do myself. I'll get the download ASAP.
Thanks for the work you put in and the clear explanation.
After reading the question again I realized my previous post visually showed the line of sight between the two points but did not actually answer the question, which is how to determine the line of sight distance. As noted by others there is a difference. The answer to the question is how do you determine the hypotenuse of a right triangle. The formula is A squared plus B squared equals C squared.
See the example below along with the solution to the bigger problem. Keep in mind that I am pretty sure that Google Earth Pro measuring tool measures horizontal distances only which gives one of the values to plug into the formula. Google Earth Pro elevation tool determines the distance in elevation between the two points for the second value to plug into the formula. If my math is correct (and I'm sure someone will let me know about it if I'm wrong) the difference between the horizontal distance and the line of sight distance is pretty small. Let's just say small enough to even satisfy Mr. Picky Pants. (just joking!!!)
Line of Sight Calculation.jpg
 
After reading the question again I realized my previous post visually showed the line of sight between the two points but did not actually answer the question, which is how to determine the line of sight distance. As noted by others there is a difference. The answer to the question is how do you determine the hypotenuse of a right triangle. The formula is A squared plus B squared equals C squared.
See the example below along with the solution to the bigger problem. Keep in mind that I am pretty sure that Google Earth Pro measuring tool measures horizontal distances only which gives one of the values to plug into the formula. Google Earth Pro elevation tool determines the distance in elevation between the two points for the second value to plug into the formula. If my math is correct (and I'm sure someone will let me know about it if I'm wrong) the difference between the horizontal distance and the line of sight distance is pretty small. Let's just say small enough to even satisfy Mr. Picky Pants. (just joking!!!) View attachment 433592
The question is the distance from Little Round Top to Bream's Hill (not Blackhorse Tavern), where Longstreet's column stalled on July 2. But I appreciate your effort to teach me how to figure the stuff out.
 
The question is the distance from Little Round Top to Bream's Hill (not Blackhorse Tavern), where Longstreet's column stalled on July 2. But I appreciate your effort to teach me how to figure the stuff out.
Thanks. Glad it helps. Here is something else I was not aware of about digitally measuring distances until a couple of days ago. When measuring a line using the Google Earth Pro measuring tool there are different options; i.e. measure a straight line between two points, measure a path using multiple points such as might be done to determine how far troops march other than in a straight line, as well as other features. Also just learned that distances can be measured using plain old Google Maps - straight line or path using multiple points. Just right click on the map and select measure distance.
 
Back
Top