Our equipment delivered the raw data required by the scheme's trigonometry. It measured the angles & distances, ground out the numbers, recorded and verified our calculations.
The following links provide detailed information on the equipment used to survey:
Mapping grid coordinates in the pre-satellite era needed a highly trained and skilled operator, who knew how to use the tools available to get the task done, and on occaison workable coordinates were supplied using just a magnetic compass.
photo courtesy J McFadden.