I believe the two pronged instrument is called the divider and the one with the pencil lead on it is the compass used to draw arcs and circles. I used the dividers to measure N.Miles on Admiralty Charts. The measurements were taken fron the Lat/Long scale at the side of the chart with them.
Sorry, we can't find any related questions. Try using the search bar at the top of the page to search for some keywords, or choose a topic and submit your own question.