104 Harritey—An Investigation of the Connexion between 
units. This conveys some idea of the dispersion and the fine definition of the 
lines photographed with the four-prism quartz-spectrograph. 
Similarly in the potassium spectrum, the following groups have been photo- 
graphed as distinct lines, but with the separation of the lines into doublets, or 
triplets in some cases, when the quantity of substance in the flame was reduced. 
| 5359°88 5112°68 4047°36 3447°49 
5802°01 5340:08 50 99°64 4044-29 3217°76 
5782-67) 5323°55 4870°4 
