Replicas and Restorations of Early Instruments by Richard A. Paselk

Richard Paselk, Curator

"Wheel" Mariner's Astrolabe

In 2015 I modified this early effort to model the earliest "open-form" mariner's astrolabe (photo above) so as not to duplicate the new heavy cast model I made in 2014. It was originally made as an interpretation of a mature Spanish/Portuguese design, c. 1560–1800, photos at left & right below). The model was derived from a photograph of two instruments in a book about early scientific instruments and instrument collecting (Michel, H. [1967]. Scientific Instruments in Art and History. New York: Viking Press). This was my first attempt at an early instrument model.

Maker's Notes

(Numbers in text refer to exploded view below)

The body was fabricated from ¼” bronze rather than the heavy (3/4") casting of a real instrument. The bronze used for the instrument body (4) and alidade (1) was from a discarded grave marker, approximately 1/4" in thickness. The original beaded pattern on the top of the marker can still be seen on portions of the instrument, the letters and numbers on the orignal marker were ground off. As can bee seen in the image of the reverse, the instrument was laid out on the back, ground side, of the marker (note the reaianing patina and salts on the casting, the result of its prior existance in contact with earth). After layout, the instrument parts were cut out with a jig saw, and finished with files. The sites on the alidade were fabricated from 14 g brass sheet, with site holes carefully drilled so they would align with the edges of the alidade. They were then soldered into file-cut grooves in the alidade with rosen-core tin-alloy solder. The hanger (3) was made from a bronze eye-bolt I had in my stocks, while the connector allowing motion in perpendicular directions was fabricated from another small piece of the marker bronze. This early effort was graduated using a good quality drafting protractor and scribe on circles cut with a large dividers. For the "pin" I used a 1/4" 20 bolt and a custom made nut I fabricated from brass rod on a lathe.

In 2015 I used a jigsaw to cut out the "weights" at the bottom of the body and then cleaned up the new cuts with files.

© R. Paselk 2013, Last modified 27 December 2020