Smithsonian Report, 1939. — Harrison 



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1. Photomicrograms Taken of Hafnium Crystals immersed in Turpen- 

 tine (LEFT) Taken With Green light, and (Right) with Ultraviolet light. 



Any particle appearing transparent in photomicrograni at left and opaque in one at right contains hafnium. 



2. Automatic Machine for Measuring. Computing, and Recording the 

 Wave lengths of Spectrum Lines. Which Has speeded up These Opera- 

 tions SOME 200 TIMES. 



Over 8 million measurements have recently besn made at the Massachusetts Institute of Technology with 

 this machine and an improved model, and it is e.xpected that a new catalog of wave lengths of spectrum 

 lines containing the results will soon be issued. Such a set of tables is badly needed, as the last systematic 

 set of measurements of this sort was made in 1911, and greatly improved methods are now available. 



