Nunes Navigation Quadrant
Finished Nunes Quadrant (front) with custom turned plumb bob and pearl bead
Nunes Navigator's Quadrant
I was inspired to make this quadrant from a description in book Latitude Hooks and Azimuth Rings by Dennis Fisher, when I found a left-over brass quadrant blank from a workshop I presented at Harvard in 2007. Though unable to find an authentic example via web searches etc., I decided to go ahead with the project. A later inquiry to the international community of scholars of early scientific instruments determined that this quadrant was most likely never made or used by western navigator's.*
As a fan of "Steampunk" and alternate reality science fiction/fantasy I present this as an instrument from an alternate reality, where Western navigators used it as a common instrument on deck to make quick measurements and navigational decisions.
For notes on my techniques for graduation and fabrication. I refer you to my discussion on making my recreation of the Zutphen Horary quadrant. The quadrant itself has an edge length of four and three quarters inch.
For this quadrant I used 3 mm Bridget font punches for the major divisions on the limb and lower case figures for my signature on the back. The text on the instrument front was made with 1.5 mm standard font figure punches. For the Nunes % scale 1.5 mm standard font number punches were used on the major divisions, while 1 mm standard font number punches were used for marking the half decade 5 division marks on both scales.
Nunes Quadrant (back) with signature near bottom edge
So how is this instrument used? Today, because the North Star is (approximately) at true north, you can determine the latitude by siting the North Star, setting the bead, then moving the string over to the percentage scale and reading the relative distance to sail one degree of longitude. In the example below the latitude is 42°, yielding a relative distance of 76%, or (0.76)(60 nautical miles/degree) = 45.6 nautical miles.
North reading = 42°
Holding the string at 42°, slide the bead to the Nunes arc
Now swing the string over to the Nunes scale and read 76%
Holding the Nunes Quadrant to make a reading
*My colleague and internet friend Nicolås de Hilster, one of the world's premier experts on European navigation tools, did a deep dive on this instrument and found that while Nunes did indeed describe this technique for finding the distance between longitudes at different latitudes, it appears it was more a technique for the navigators use on paper below decks after measurements/sightings were made on deck.