328 THE CANADIAN NATURALIST. [Oct 



the Association has striven to promote. By another application 

 of the same beautiful art, in connection with clock-work, the mo- 

 mentary 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 proportion 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 

 large 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 enquiry, 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 enquiry 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-de- 

 stroying cold, far above our mountain tops, have obtained innume- 

 rable data, in all seasons of the year, through a vast range of ver- 

 tical 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 view of Leslie, 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 (s). 



The proportion of carbonic acid gas in the atmosphere at great 

 heights is not yet ascertained ; it is not likely to be the same as 

 that generally found near the earth ; but its proportion may be 

 more constant, since in those regions, it is exempt from the influ- 

 ence of the actions and reactions which are always in progress on 

 the land and in the water, and do not necessarily compensate one 

 another at every place and at every moment. 



Other information bearing on the constitution of the atmo- 

 sphere comes to us from the auroral beams and other meteoric lights 

 known as shooting stars. For some of these objects not only ap- 

 pear at heights of ten, fifty, and 100 or more miles above the earth, 

 but at the height of fifty miles it is on record that shooting star* 



(s) Reports of the British Association for 1862, 1863, 1864. 



