One of my favorite memories is visiting my father in his office in the 1960s (he was a civil engineer). He had a big mechanical calculator which was very impressive. He keyed in numbers then hit the button and you knew some calculating was going on by the hum and clatter of the machine. I asked him if that was the answer but he said no he had to look it up in the book (log table I assume or maybe arc tangent table), that was disappointing to me.
I found an old book of log and functions tables when we moved the office so I played with it a little bit, I did a Pythagorean calculation using common logs. Those old books were ingenious how they were setup. By the time I was done my paper was full of penciled calculations and log numbers all over it.
?ÿWe have the old traverse sheets, distance, bearing, cos, sine, lat, dep, north, east. So I wondered how they multiplied those numbers. I know they had logarithmic functions but these are the natural cos etc.
Dad told me he had a Marchant calculator in the 1960s. The one I found did four functions so I guess they didn't need to add the logs to multiply:
http://www.vintagecalculators.com/html/marchant_figurematic.html
When I started in the late 70's I worked for a guy who started in the late 20's.?ÿ He used to carry around a pocket function book, it had sine, cosine, tangent, cotangent, cosecant and secant.?ÿ They were to four places and he used all six functions because he always multiplied, never divided (calculated by hand or a curta). And we taped and used a 20 second transit (breaking down sections).?ÿ Three to four man crews.?ÿ
I've always wanted to learn how to do a star shot (might be the wrong term) to determine your location. Are there any YouTube channels with demonstrations? Not that I would ever use it, just want to see how things were done before my time. I believe they were called azimuth marks (like church steeples) in NGS datasheets, that did something similar, correct?
I apologizes, the oldest instrument I've used is a Geodimeter!
You can observe Polaris for determining astronomic north. Any elementary Surveying text has the method and calculations.
Determining location from the stars is more difficult. There are some navigation texts on line.
The navigation texts will give the basics and older books give several calculation method using tables.?ÿ But for navigation they were happy with a km or a mile accuracy, so there are many subtleties ignored.?ÿ
Because of the low accuracy, surveyors rarely found position by astronomical calculations.?ÿ For some important lines, Mason and Dixon, for instance, would spend every clear night for two weeks making and averaging stellar observations to start a line within 200 ft of the latitude they wanted. Longitude with any precision was even more difficult until time distribution became easier.
Recommended text at http://www2.unb.ca/gge/Pubs/LN49.pdf. (University of New Brunswick Lecture Notes ?ÿLots of good info. To perform and reduce the work will involve specialized equipment ( e.g. a Wild T-4) and a good astronomical almanac. I knew some of the NGS observers?ÿ
Also shown is a screen capture from the US NGS site commemorating the 120th anniversary of the Gaithersburg (MD) International Latitude Observatory.
Some interesting photos here: https://photolib.noaa.gov/Collections/Geodesy/emodule/519/eitem/6997
More pictures including Wild T-4 in use are: https://photolib.noaa.gov/Collections/Coast-Geodetic-Survey/Geodesy/Astronomic-Latitude-and-Longitude/emodule/961/egallery/497/epage/3. (See pages 1 and 2 as well.
Due to insufficient attention while posting, some of the links in posts above include spurious punctuation. Remove the ending period in the links to access the referenced resource.
It would also be useful to recognize how celestial and terrestrial frames are related.
mea culpa?ÿ
