SIR WILLIAM HUGGINS, K.C.B, O.M. 187 



believe that all nebulae might be found to consist of stars if 

 instruments powerful enough could be made. Lord Rosse 

 showed later that at the same time that the number of clusters 

 may be increased by the resolution of supposed nebulae, other 

 nebulous objects are revealed ; and thus it appears that however 

 large the telescopes were made, the decision would only be 

 pushed a few steps farther off. In 1864 Huggins made that 

 cardinal discovery, which closed the battle between monster 

 telescopes and disclosed an essential difference between nebulae 

 and stars. The riddle was solved by the use of a relatively 

 small telescope, which yet collected enough light to enable the 

 observer to judge of the nature of the light when analysed by 

 the spectroscope. A glance was enough to show that the 

 spectrum was entirely unlike that of a star. We can well 

 understand Muggins's first shock of incredulit3^ " At first I 

 suspected some derangement had taken place, for no spectrum 

 was seen, but only a short line of light perpendicular to the 

 direction of dispersion." In all the three previous years, during 

 which he had passed star after star in spectroscopic review, 

 he had never found a case in which the spectrum did not 

 present the whole array of colours, broken only here and 

 there by narrow dark intervals or lines. Here in the small 

 planetary nebula in Draco was an entirely new case. The light 

 was nearly monochromatic. A few more moments only were 

 needed to assure him that the spectrum was that of a luminous 

 gas, exhibiting but very few lines and those bright. The nature 

 of this gas had to be found, and the work of observation had 

 to be extended. In the course of the next four years Huggins 

 had examined the spectra of about seventy nebulae. About two- 

 thirds of them gave a continuous spectrum, the rest gave a 

 spectrum of bright lines. Recent spectroscopic observations 

 suggest that nebulae which are of spiral type have a continuous 

 spectrum, and that those nebulae which either have an irregular 

 form, or are ring-shaped or disc-shaped like a planet, exhibit 

 spectra of bright lines. Huggins's investigation of the nebula 

 in Andromeda has contributed in no small degree to the care 

 with which this large inquiry has been carried on. 



In his search for the origin of the bright lines in the nebular 

 spectrum, Huggins identified two of the lines with hydrogen 

 and originally ascribed the brightest green line to nitrogen ; 

 but later work, to which he himself contributed in open-minded 



