i82 SCIENCE PROGRESS 



of the Sun was also investigated. In 1876, which we may 

 recall as the year following Dr. Huggins's marriage with Miss 

 Margaret Murray, the reflector was mounted in place of the 

 achromatic telescope. During the next six years, 1876-82, the 

 reflector was used in the study of planetary spectra and, after 

 preliminary work had been carried out to gain experience in 

 photographing spectra, the spectroscope with a single prism 

 of Iceland spar was constructed and got into adjustment for 

 obtaining by photography the ultra-violet spectra of the stars 

 and nebulas. The comets of 1881 and 1882 demanded attention ; 

 and it may be surmised that it was the unexpected appearance 

 of these bodies which led Huggins to have a change made in 

 the equatorial mounting, whereby it should be possible to keep 

 both reflector and refractor permanently in adjustment and 

 ready for use in any emergency. These telescopes had previously 

 been interchangeable on the mounting, either of them being 

 counterpoised by a dead weight at the end of the declination 

 axis. But in 1883 the dead counterpoise was abolished, and 

 a new double declination axis was made, carrying the reflector 

 at one end and the refractor at the other, one thus serving 

 as a counterpoise to the other, and each being movable in 

 declination independently of the other. With the new arrange- 

 ment it was easy to pass from investigation of ultra-violet spectra 

 with the reflector to visual observations of Nova Aurigas with 

 the refractor. New spectroscopes were designed and constructed 

 for each ; and thus either a dense glass prism or a grating was 

 available with the one, whilst a spectroscope with two prisms of 

 Iceland spar was arranged for the other. 



This brief summary of the development of his instrumental 

 requirements serves to show the activity with which Huggins 

 moved ahead in his researches. It is curiously similar to the 

 development which marked the advance a generation later at all 

 points, with one large difference — namely, that the earlier advance 

 must be regarded as due mainly to the pioneering efforts of one 

 man, whilst the later gained its impetus from the confidence 

 inspired by those efforts in a widespread movement of collabo- 

 ration. 



The results and records of Huggins's life's work are contained 

 in two volumes, bearing the title Publications of Sir William 

 Huggins's Observatory. The first volume, Atlas of Representative 

 Stellar Spectra, was published in 1899 and contains "the later 



