92 



1. Sodium. 5. Iron. 9. Zinc. 13. Hydrogen. 



2. Calcium. 6. Chromium. 10. Strontium. 14. Manganese. 



3. Barium. 7. Nickel. 11. Cadmium. 15. Aluminium. 



4. Magnesium. 8. Copj^er. 12. Cobalt. IG. Titanium. 



Around this gaseous envelope there is a still moi'e attennuated one, 

 composed mainly of the lightest known element, viz., hydrogen. It is 

 this envelope which gives rise to the peculiar flame-like protuberances 

 that are seen surrounding the sun during an eclipse. Thanks to the 

 labours of Lockyer and Janssen we are now enabled to examine this 

 envelope, which is termed the Chromosphere, by the spectroscope, without 

 waiting for an eclipse, and it has been found that it extends to an average 

 height of 5,000 miles, that it is subject to most violent storms which 

 sometimes raise it in clouds 50,000 miles high, leaving depressions at 

 other parts, through which the cooler portions' of the sun can be seen, thus 

 giving rise to the phenomena known as sun spots. We are thus enabled 

 by this beautiful instrument to dive deeply into the mystery of that orb 

 which has been the wonder of all ages. But not only so, we can by its 

 aid study those far off worlds whose light takes thousands of years to 

 reach us, and we can also gain deep knowledge of those erratic phenomena, 

 the comets, which have before time so terrified our ancestors by their 

 sudden and startling appearance. What is yet more remarkable is, tha t, as 

 Huggins has shewn us, it is possible to determine whether a star is mov- 

 ing to or from us, and even to calculate the velocity with which such 

 motion is taking place ; in this way he has demonstrated that Sirius is 

 receding from the earth at the rate of 41 miles per second. 



Time will not admit of my explaining to you how by 

 the aid of the spectorscope we can also examine the nature of 

 colouring matter in coloured solutions ; how the smallest speck 

 of human blood can be detected by the characteristic absorption 

 bands which it produces, or how Sorby has traced the changes 

 taking place in tree foliage from summer to winter, and many other 

 equally interesting fields of investigation. Nor can I stay to explain to 

 you the last, bvit by no means the least contribvition to the subject, except 

 to state that within the last year Sir J. AUene has shewn us that it is not 



