ADDRESS. lv 



of some nebuhe, by the giant mirror of Lord Rosse, afforded ground for 

 opposing the speculation of Herschel and the reasoning of Laplace, which 

 required for their very starting-point the admission of the existence of thin 

 gaseous expansions, with or without points or centres of incipient condensa- 

 tion, with or without marks of internal movement. The latest results, how- 

 ever, of spectral analysis of stars and nebulas by Mr. Huggins and Professor 

 W. A. Miller, have fairly restored the balance. The nebulas are indeed found 

 to have in some instances stellar points, but they are not stars ; the whole 

 resembles an enormous mass of luminous gas, with an interrupted spectrum 

 of three lines, probably agreeing with nitrogen, hydrogen, and a substance at 

 present unknown*. Stars tested by the same accurate hands are found to 

 have a constitution like that of our own Sun, and, like it, to show the pre- 

 sence of several terrestrial elements — as sodium, magnesium, iron, and very 

 often hydrogen. While in the Moon and Venus no lines whatever are found 

 due to an atmosphere, in Jupiter and Saturn, besides the lines which are 

 identical with some produced in our own atmosphere, there is one in the red, 

 which may be caused by the presence of some unknown gas or vapour. Mars 

 is still more peculiar, and enough is ascertained to discountenance the notion 

 of his redness being due to a peculiarity of the soil f. 



To aid researches into the condition of celestial bodies, the new powers of 

 light, discovered by Niepce, Dagucrre, and Talbot, have been employed by 

 Bond, Draper, De la Rue, and other astronomers. To our countryman, in 

 particular, belongs the honour of successful experiments on the rose-coloured 

 flames which extend from certain points of the sun's border during an 

 eclipse ; as well as of valuable contributions through the same agency to that 

 enlarged survey of the physical aspect of the moon, which, since 1852, the 

 Association has striven to promote. By another application of the same 

 beautiful art, in connexion with clock-work, the momentary changes of 

 magnetic force and direction, the variations of temperature, the fluctuations 

 of atmospheric pressure, the force of the wind, the fall of rain, the propor- 

 tion of ozone in the air, are registered in our observatories ; and thus the 

 inventions of Ronalds and his successors have engaged the solar rays in 

 measuring and comparing contemporaneous phenomena of the same order 

 over lar£ e parts of the globe — phenomena some of which are occasioned by 

 those very rays. 



As we ascend above the earth, heat, moisture, and magnetic force decrease, 

 the velocity of wind augments, and the proportion of oxygen and nitrogen 

 remains the same. The decrease of heat as we rise into the air is no new 

 subject of inquiry, nor have the views respecting it been very limited or very 

 accordant. Leslie considered it mathematically in relation to pressure ; 

 Humboldt gave the result of a large inquiry at points on the earth's surface, 

 unequally elevated above the sea ; and finally, Mr. Glaisher and Mr. Coxwell, 

 during many balloon ascents to the zones of life-destroying cold, far above 

 our mountain tops, have obtained innumerable data, in all seasons of the year, 

 through a vast range of vertical height. The result is to show much more 

 rapid decrease near the earth, much slower decrease at great elevations ; 

 thus agreeing in general with the decrease of density, and yet throwing no 

 discredit on the determinations of Humboldt, which do not refer to the free 

 atmospheric ocean, but to the mere borders of it where it touches the earth, 

 and is influenced thereby J. 



* Proc. Roy. Soe. and Phil. Trans. 1864. t Phil. Trans. 1864. 



t Reports of the British Association for 1862, 1863, 1864. 



