This spectroscope was made by Louis Jules Duboscq 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)
	A drawing of an "early spectroscopist" taken from The Use of The Spencer Spectrometer, 1938.  This drawing depicts a spectroscope similiar to the one above. A gas jet is positioned at the right hand side of the picture along with a sample holder. In the foreground is a candle that is illuminating an arbitrary scale that is reflected off the back surface of the prism and is superimposed on the spectrum when viewed through the telescope. This method was generally used for identification of chemical elements. Instruments which had finely divided scales with which the position of the telescope relative to the prism could be measured were used for making refractive index and wavelength measurements.
	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.