This spectroscope was made by Jules Dubosq who manufactured the first commercial spectroscopes around 1861. Prior to that time such instruments were custom built.  This instrument consists of three arms and a central platform on which the prism would be placed. A metal cover with sized holes for each arm  covers the prism. The arm on the right in the picture is the telescope through which the spectra would be viewed and consists of a collimating lens at the left end of the tube, another lens just to the right of the draw tube knob, and an eyepiece which consists of an eye and field lens. The shorter central arm was used to project a measurement scale onto the prism . The scale insert for this arm is missing. The left arm is the collimator and consists of  an adjustable slit , which is partially covered by a small prism,  and a collimating lens on the near end. The collimating arm and the arm with the measurent scale are fixed relative to one another.  The telescope can travel between the other two arms. (1)
	The spectroscope can be adjusted vertically over a 5" range.
	"J Duboscq a Paris No. 186"

1. Some of the information on this page was supplied by Dr. Ben Smith (bwsmith@ufl.edu), Department of Chemistry, University of Florida. Dr. Smith  has #609 in his collection.