52 



Dr. W. Huggins and Mrs. Huggins. [^ a y 2. 



seven nebulae were approaching the earth with velocities such that, 

 having respect to the earth's motion at the different times of observa- 

 tion, they all gave a sensible shift corresponding to 67 =b 15 miles in a 

 second. There is little doubt in my mind, therefore, from these com- 

 parisons, which, considering the strong evidence we possessed before 

 of the relative positions of the nebular line and of the magnesium 

 line, are strictly speaking supplementary and confirmatory evidence 

 only, that this line of the gaseous nebulae is not produced by " the 

 remnant of the magnesium fluting."* 



In the diagram on page 134 (' Roy. Soc. Proc.,' vol. 43), Mr. Lockyer 

 represents this nebular line followed by fine lines, which gives it the 

 appearance of a fluting similar to that of the magnesium band placed 

 above. I am unable to find in the paper any authority for this repre- 

 sentation of the line. In another placef Mr. Lockyer says : " On one 

 occasion, at Greenwich, it was recorded as a fluting in the spectrum 

 of the nebula in Orion." Mr. Maunder's words are :J " None of the 



* [The following observations were made at Greenwich in 1884 on the motion of 

 the nebula in the line of sight : — 



" February 15. Mean of four observations, 31 miles of approach." 

 Eemarks : Measures purely tentative. 



" February 18. Mean of four observations, 51 miles of approach." 



Eemarks : The F line in the spectrum of the nebula was faint, very much fainter 

 than the line at X 5005. The measures, therefore, are not trustworthy. 



" March 10. With neither one nor two prism trains, after very careful direct 

 compari-on (the light from the comparison tube being weakened until it could be 

 compared directly with the light from the nebula), could any displacement be 

 detected ; the coincidence of two spectra was evidently very close. 



" March 12. Spectrum too faint for measures. The hydrogen spectrum was 

 brought down to almost exactly the same intensity as the light from the nebula, 

 and direct comparison showed coincidence as complete as could be detected con- 

 sidering the faintness of the two spectra. . . No part of the nebula which was 

 sufficiently bright to show the pointer well on the 5005 line showed any marked 

 displacement, but at a point a little preceding the Trapezium it was thought that 

 the pointer did not seem perfectly central on the line but a little (perhaps 

 certainly not more) towards the red " (' Grreenwich Spectroscopic and Photographic 

 Results,' 1884). 



Also in 1887, six determinations on the same night. 



" Oct. 25. Measured 37 '8 miles of approach. Estimated 24 miles of approach. 



8-3 

 7 1 

 38 -4 

 24-5 

 10-8 



recession. 



recession. 



approach. 



9-3 

 9-3 

 24 

 24-0 



9-3 



approach. 



recession. 



recession . 



Eemarks : Lines in nebula very faint and bisections very rough." 



(' Grreenwich Spectroscopic and Photographic Eesults,' 1887). — May 13.] 



f Programme Royal Society Soiree, May 9, 1888, p. 12. 



X ' Greenwich Spectroscopic Eesults,' 1884, p. 5. 



