|William Ludlow Reconnaissance Map of the Black Hills 1874|
Soon after, in 1875, Col. Richard Irving Dodge completed an Exploration Survey of the area.. In the early surveys, Spearfish Mountain was named Black Butte.
|SAHS members with surveying tools|
Burt's Solar Compass, an improved surveying tool was used. This tool determined the position of the sun, and occasionally the moon, with astronomical tables to run more accurate lines.
The pay for the Engineering company for the 1877 survey was $6 per mile for prairie and $10 per mile for mountain terrain.
Townships were surveyed at 36 miles square.
The Black Hills Base Meridian line was established along the Wyoming-South Dakota border at milespost 69 on Aug 13, 1878.
|calculators used by surveyors|
Tools improved throughout the years and calculators were lugged around for basic mathematics. Calculations of trigonometry were manual until 1972 when Hulett Packard introduced the HP-35 for $400.
|on the left is a Hulett Packard HP-45|