NavList:

From: David Pike:
"Lt Everest and Radhanath Sikdar will long be remembered, but who remembers
the name of the poor chap (or donkey) who was required to carry the
theodolite up those mountains?"

I didn't recognize the name Radhanath Sikdar, but I suspected and verified he was the Survey of India computer who discovered Everest was the highest peak in the world. That wasn't obvious since it was only one of many high peaks observed at great distance (more than 100 km, I think). Direct access to the peaks or observation from close range were not options since Nepal would not give permission.

The Survey of India is no longer run by Britain but still exists. Their web site (in English) is easy to find.

Regarding compasses, they were a normal part of the transits used by ordinary (not geodetic) surveyors in the US in the early 20th century. For instance, see this 1916 catalog by Berger, one of the big instrument makers:

https://archive.org/details/engineeringsurv00sonsgoog/page/n51/mode/1up?view=theater

To find true north, surveyors could use a sun compass, or a solar attachment could be installed on a transit:

https://archive.org/details/engineeringsurv00sonsgoog/page/n73/mode/1up?view=theater

https://compleatsurveyor.com/eReferenceSolar/eRefSolar.html

I've read that solar attachments gradually went out of favor. Instead, surveyors sighted the Sun through the transit's regular telescope and did the math that the solar attachment had done mechanically.

An 1889 article by James Keeler notes the endless confusion due to surveys based on the magnetic needle. It suggests that every city ought to have a pair of monuments set on a true meridian, and require by law that surveyors test their compasses annually. He helped Santa Clara County in California establish such a mark:

absabs.harvard.edu ... link

His temporary mark on the board fence must have been at the intersection where Meridian Ave terminates at Park Ave (N 37.326 W 121.914). An 1899 map shows an oval horse racing track north of the intersection, where the tract of houses is today. Surely that's the "fair ground" mentioned in the article. I wonder if traces of the meridian marks still exist under the pavement.

nationalmap.gov ... link

Keeler made quite a name for himself at nearby Lick Observatory. I'm a little surprised such an eminent astronomer took this project. By the way, I checked a few of the azimuths in his Polaris table. They're accurate within the 10" precision of the table. (Add 8 h to convert times to UT.)

--
Paul Hirose
sofajpl.com