Scientific Lectures. 13 3 



SCIENTIFIC LECTITEE-IL 



THE CHEMISTRY OF THE SUN. 



By Professor George F. Barker, op Yale College, Dec. 14, 1871. 



Ladies and Gentlemen. — The sun has at all times been an object 

 of interest to dwellers upon the earth. Not alone to the man 

 of science, learning from Copernicus the sun's absolute auto- 

 oracy, has this desire for more knowledge come; the common 

 laborer in the field shares it with him, as he daily witnesses 

 the glorious march of the day-god across the heavens, and beholds the 

 wondrous metamorphoses effected by his beams ; but at the utterly 

 impassable distance at which he dwells, how shall this knowledge be 

 attained ? Who shall bridge the separating chasm and bring to us 

 news of his composition and physical condition ? The telescope 

 offered the first partial solution of the question. No sooner was the 

 first astronomical telescope constructed, than Galileo turned it upon 

 the sun and accurately observed many of its phenomena ; and, from 

 1611 to the present day, the telescopic method of investigation, per- 

 fected by the refinements of modern science, has been diligently 

 applied to the problem and has collected a vast mass of facts of the 

 greatest scientific value. The sun's distance, his size and weight, the 

 curiously mottled appearance of his surface, with its faculge and spots, 

 and his time of rotation ; these, with other and similar data, we owe 

 to the telescope ; but, notwithstanding all this, the problem of the 

 sun's constitution remained unanswered. No one knew whether the 

 sun was a hot or a cold body ; whether it was liquid or gaseous, or 

 whether it was uniform in character throughout, or made up of con- 

 centric layers. True, Sir William Herschel, resting mainly upon data 

 collected by Wilson in 1769, from observations upon the spots, pro- 

 posed in 1802 a plausible theory on the subject, a theory which 

 admitted the previous notion that the spots were cavities in the solar 



