[D9246AAB], Letter from Louis Glass to Thomas Alva Edison, February 19th, 1892
https://edisondigital.rutgers.edu/document/D9246AAB
→ View document with UniversalViewer
→ View document on Archive.org
→ Re-use this digital object via a IIIF manifest
Title
[D9246AAB], Letter from Louis Glass to Thomas Alva Edison, February 19th, 1892
Author
Recipient
Date
1892-02-19
Type
Folder/Volume ID
D9246-F
Microfilm ID
133:735
Document ID
D9246AAB
Publisher
Thomas A. Edison Papers, School of Arts and Sciences, Rutgers University
Has Version
Item sets
Transcription
San Francisco, CAL., February 19th, 1892
Thomas Edison, Esq.,
Orange, New Jersey
Dear Sir:
When engaged in Hydraulic Mining, I sometimes ran long [preliminary gulch?] lines, sighting from hill to hill, and a traveling engineer gave me the following ready formula for determining the approximate curvature of the earth. I have never seen it in print, and thought it would be useful to you in connection with your induction telegraph system at sea.
It is 1/7 of the square of the distance in miles gives the curvature in feet.
Example:
Curvature for miles: 10 x 10 = 100 / 7 = 14.3 x 4 = 57.2 Pt.
Curvature for miles: 20 x 20 = 400 / 7 = 57.1 x 4 = 228 Pt.
Very truly yours,
[Signed Louis Glass]
Thomas Edison, Esq.,
Orange, New Jersey
Dear Sir:
When engaged in Hydraulic Mining, I sometimes ran long [preliminary gulch?] lines, sighting from hill to hill, and a traveling engineer gave me the following ready formula for determining the approximate curvature of the earth. I have never seen it in print, and thought it would be useful to you in connection with your induction telegraph system at sea.
It is 1/7 of the square of the distance in miles gives the curvature in feet.
Example:
Curvature for miles: 10 x 10 = 100 / 7 = 14.3 x 4 = 57.2 Pt.
Curvature for miles: 20 x 20 = 400 / 7 = 57.1 x 4 = 228 Pt.
Very truly yours,
[Signed Louis Glass]