...August 29, 1864, I directed the telescope for the first time to a planetary nebula in Draco. The reader may now be able to picture to himself to some extent...not about to look into a secret place of creation? I looked into the spectroscope. No spectrum such as I expected! A single bright line only! At first...

...wrote, "I directed the telescope for the first time to a planetary nebula in Draco," and with hesitation "put my eye to the spectroscope. Was I not about to look into a secret place of creation?" What he saw was not what he expected. The spectroscope showed not the continuous spectrum characteristic...