ON SPECTROSCOPY. 7 



And now let me turn in conclusion to one more aspect of this great 

 undertaking. We have here collected not only the instruments which 

 represent the most advanced posts of modern science, but we have 

 not a few of the men whose genius and perseverance have led the way 

 thither ; men who stand in the forefront of our battle against ignorance 

 and prejudice and against the host of evils which a better scientific 

 education must certainly dispel ; we have men whose powers are com- 

 petent for, and whose very presence is an inspiration to further progress. 

 But, while taking this first opportunity of offering them a hearty 

 welcome, I shall however best consult their feelings and your wishes 

 by abstaining from any panegyric upon them in their presence, and by 

 giving them an opportunity of speaking, and you of hearing them, 

 upon some of their own subjects in illustration of the remarkable 

 instruments which they have with so much pains and trouble brought 

 under our view. 



Mr. WARREN DE LA RUE, in proposing thanks to the President, 

 strongly expressed a hope that the collection might be the nucleus of 

 a permanent one. 



The addresses arranged for the day were then delivered as follows : 



ON SPECTROSCOPY APPLIED TO THE HEAVENLY BODIES OTHER 



THAN THE SUN. BY WILLIAM HUGGINS, D.C.L., LL.D., F.R.S., 



Corresponding Member of the Institute of France. 



There is not much that is very new in the subject on which I have 

 been asked to speak. I will give, therefore, a short summary of the 

 methods and present state of this part of science. It is, too, not inap- 

 propriate in this great collection of instruments to say something of the 

 methods and instruments by which the results have been obtained. 



When the spectroscope is to be applied to the heavenly bodies, the 

 first consideration which presents itself is as to the method by which 

 the image of the apparently moving heavenly body shall be made to 

 remain steadily under observation. This effect of the moving platform 

 on which the astronomer finds himself may be counteracted in two 

 ways, either by mounting the telescope on an axis parallel to the- earth's 

 axis of rotation, so that the telescope will follow the star by a uniform 



