40 



Dr. W. Huggins and Mrs. Huggins. 



[May % 



This commonalty furnishes a strong argument in favour of the 

 suggestion that the aurora line is the remnant of the manganese 

 fluting, for it is practically certain that the fluting seen in the spectra 

 of meteor-swarms is due to manganese. 



Further, in the aurora the line which I have ascribed to the 

 manganese fluting is associated with other lines and flutings, and it 

 is also associated with the same lines and flutings in the spectra of 

 meteor- swarms. These again, it is important to note, are exactly 

 the lines and flutings which are brightest in the spectra of meteorites 

 in the laboratory at the temperature at which the manganese fluting 

 is best visible. 



These shortly are the reasons why I suggested that further enquiry 

 was necessary on this point, and the importance of Dr. Huggins's 

 observation is therefore very great.] 



IV. a The Accurate Determination of Carbonic Acid and 

 Moisture in Air." By J. S. HALDANE, M.A., M.B., and 

 M. S. Pembret, Pell Exhibitioner of Christ Church, Oxford. 

 (From the Physiological Laboratory, Oxford.) Communi- 

 cated by Professor J. Burdon Sanderson, F.R.S. Received 

 April 8, 1889. 



V. " On the Spectrum, Visible and Photographic, of the Great 

 Nebula in Orion." By William Huggins, D.C.L., LL.D., 

 F.R.S., and Mrs. HUGGINS. Received April 11, 1889. 



[Plate 1.] 



I have added the name of Mrs. Huggins to the title of the paper, 

 because she has not only assisted generally in the work, but has 

 repeated independently the delicate observations made by eye. 



In the year 1882 I had the hononr to lay before the Royal Society 

 a note on the photographic spectrum of this nebula, in which I 

 described a new bright line in the nltra-violet, to which I gave a 

 wave-length of about 3730. In addition to this new line, the lines of 

 hydrogen, H/3 and H7, which I had discovered by eye in my early 

 observations on the visible spectrum, were to be seen upon the plate. 



On acconnt of the faintness of the object the slit had been made 

 rather wide, and for this reason the character of the line and its 

 position, as I stated in the paper, could not be ascertained with the 

 accuracy which I desired. 



On the 5th February, 1888, a photograph of the spectrum of this 



