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SUMMARY OF CrRRENT RESEARCHES RELATING I'd 



of spectrometers and it is well counterbalanced, features which will 

 doubtless make for long wear and freedom from shake. 



Both telescope and collimator may be eiven small altitude and 

 azimuth adjustments on tbeir supports, and these adjustments do not 

 necessitate any deformation of the tubes, a grievous fault of design in 



many of the inferior instruments of this class. Both telescope and 

 collimator also have rack focussing, while the eye- piece of the telescope 

 has helical focussing with a diopter scale. The slit is of a very simple 

 nature and is easy to clean. 



Tested in the Optical Engineering Laboratory of the Imperial 



