128 ANNUAL OF SCIENTIFIC DISCOVERT. 



vaguely, a similar influence throughout the whole planetary system, and 

 possibly far beyond. The magnetic conditions and changes of the earth 

 itself come into direct testimony here; so general and strictly coincident over 

 its surface, as to give us assurance that the total globe is in a definite mag- 

 netic state; and capable, through this state, of affecting other worlds, as 

 well as the little needle which man makes his index here of this mysterious 

 force. Edinburgh Review. 



ON THE NATURE OF FLAME AND THE CONDITION OF THE SUN'S 



SURFACE. 



The following paper, on the above subject, by Professor John W. Draper, 

 is published in the L. E. & D. Phil. Magazine, Vol. XV., page 90: 



Among the recent publications on photo-chemistry, there is one by Pro- 

 fessor Dove, on the Electric Light (Phil. Mag., Nov., 1857), which will doubt- 

 less attract the attention of those interested in that branch of science. Ex- 

 amination by the prism, and by absorbing and reflecting colored bodies, 

 leads him to the conclusion that it is necessary to consider the luminous ap- 

 pearance as having twodistict sources: First, the ignition or incandescence 

 of the material particles bodily passing in the course of the discharge ; sec- 

 ondly, the proper electrical light itself. As respects the first, he illustrates 

 its method of increase from low to high temperatures by supposing a 

 screen to be withdrawn from the red end of the spectrum through the col- 

 ored spaces successively towards the violet; and that of the latter from the 

 bluish brush to the bright Leyden sparks, by a like screen drawn from the 

 violet towards the red. 



The true electric light exhibits properties resembling those observed in 

 actual combustions, as though there was an oxidation of a portion of the 

 translated matter when the spark is taken in air. The order of evolution of 

 rays in this instance happens to be the same as in the second illustration of 

 Professor Dove, that is, from the violet to the red. There are certain facts 

 connected with these appearances of color which are not generally known, 

 and deserve to be pointed out, 



In the Philosophical Magazine (February, 1848), I showed, experimentally, 

 that there is a relation between the color of a flame and the energy with 

 which the combustion giving rise to it is going on. The more vigorous and 

 complete the combustion, the higher the refrangibility of the light. A flame 

 burning in its most tardy and restricted way emits rays that are red; but 

 burning in its most complete and effective manner, rays that are violet. In 

 intermediate states of combustion, the intermediate colors are evolved in 

 their proper order of refrangibility. 



The flame of a candle or lamp consists of a series of concentric luminous 

 shells, surrounding a central dark core. These shells shine with different 

 colors, the innermost one immediately in contact with the dark core being 

 red, and having a temperature of 977 F. Upon this, in their proper order 

 of refrangibility, are shells, the light of which is orange, yellow, green, blue, 

 indigo, violet. When we look upon such a flame, the rays issuing from all 

 the colored strata are received by the eye at once, and impress us with the 

 sensation of white light. 



The differently colored shells, of which a flame thus consists, may be 

 easily parted out from one another, and demonstrated by a prism. Their 

 cause is the slower rate at which combustion occurs at points more and more 



