1869.] The President's Address. 583 



Meanwliile the same thing had been independently observed 

 in another part of the world. After having observed the remarkable 

 spectrum of the prominences during the total eclipse, it occuiTed 

 to M. Janssen that the same method might allow the prominences to 

 be detected at any time; and on trial he succeeded in detecting 

 them the very day after the eclipse. Shortly after Mr. Lockyer's 

 communication of his discovery, Mr. Huggins, who had been inde- 

 pendently engaged in the attempt to render the prominences visible 

 by the aid of the spectroscope, succeeded in seeing a prominence as 

 a whole by somewhat widening the slit, and using a red glass to 

 diminish the glare of the light admitted by the sht, the prominence 

 being seen by means of the C line in the red. 



One of the most striking results of the habitual study of these 

 prominences is the evidence they afford of the stupendous changes 

 which are going on in the central body of our system. Promi- 

 nences, the heights of which are to be measured by thousands and 

 tens of thousands of miles, appear and disappear in the course of 

 some minutes ; and a study of certain minute changes in the bright 

 line F, which receive a simple and natural explanation by referring 

 them to proper motion in the glowing gas by which that hne is 

 produced, and wliich we see no other way of accounting for, has 

 led Mr. Lockyer to conclude that the gas in question is sometimes 

 travelling with velocities comparable with that of the earth in its 

 orbit. Moreover these exhibitions of intense action are frequently 

 found to be intimately connected with the spots, and can hardly 

 fail to throw hght on the disputed question of their formation. 

 Nor are chemical composition and proper motion the only physical 

 conditions of the gas which are accessible to spectral analysis. By 

 comparing the breadth of the bright bands (for though narrow 

 they are not mere lines) seen in the prominences with those observed 

 in the spectrum of hydrogen rendered incandescent under different 

 physical conditions, Dr. Frankland and Mr. Lockyer have deduced 

 conclusions respecting the pressure to which the gas is subject in 

 the neighbourhood of the sun. 



The President next j)roceeded to congratulate the Association 

 on the successful completion of the great Southern telescope, a 

 description of which appeared in our pages a short time ago. The 

 telescope, constructed by Mr. Grubb, of Dublin, is now erected at 

 Melbourne, and in the hands of Mr. Le Sueur, who has been 

 appointed to use it. Before its shipment it was inspected in Dublin 

 by the committee appointed by the Eoyal Society to consider the 

 best mode of carrying out the object for which the vote was made 

 by the Melbourne legislature ; and the committee speak in the 

 highest terms of its contrivance and execution. We may expect 

 before long to get a first instalment of the results obtained by a 

 scrutiny of the southern heavens with an instrument far more 



