1865.] Astronomy. 205 



the following manner : — A bridge of luminous matter, of the same 

 apparent luminosity as the surrounding photosphere, appears to cross 

 over the umbra of the spot unaccompanied by any penumbra. There 

 is good reason to think that this bridge is above the spot, for were the 

 umbra an opaque cloud, and the penumbra a semi-opaque cloud, both 

 being above the sun's photosphere, it is unlikely that the spot would 

 break up in such a manner that the observer should not perceive some 

 penumbra accompanying the luminous bridge. Finally, detached 

 portions of luminous matter sometimes appear to move across a spot 

 without producing any permanent alteration. From all this it was 

 inferred that the luminous photosphere is not to be viewed as com- 

 posed of heavy, solid, or liquid matter, but is rather of the nature 

 either of a gas or cloud, and also that a spot is a phenomenon existing 

 below the level of the sun's photosphere. The paper concluded with 

 theoretical considerations more or less probable. Since the central or 

 bottom part of a spot is much less luminous than the sun's photosphere, 

 it may perhaps be concluded that the spot is of a lower temperature 

 than the photosphere ; a'nd if it be supposed that all the sun's mass at 

 this level is of a lower temperature than the photosphere, then we 

 must conclude that the heat of our luminary is derived from without. 



Dr. Eeichenbach, of Vienna, has made a curious experiment. The 

 existence of aerolites, meteors, &c, which frequently fall to the earth, 

 has led some persons to the belief that the cosmical space is filled 

 with a dust which sometimes becomes agglomerated so as to form large 

 and small meteors, while at other times it reaches the surface of our 

 earth in the form of an impalpable powder. Dr. Eeichenbach has 

 attempted to show the existence of such a powder, by collecting some 

 of the dust from the top of a high mountain, which had never been 

 touched by spade or pickaxe; upon analysis he found this dust to 

 consist of almost identically the same elements of which meteoric 

 stones are composed — nickel, cobalt, iron, and phosphorus. The 

 doctor considers that we must look for the source of phosphorus in 

 our soils to this mysterious invisible rain, which henceforth must be 

 regarded as quite as necessary for vegetation as the water which falls 

 from the clouds. This very pretty theory would stand more chance 

 of being believed in by scientific men if there were no such thing as 

 wind ; but under the present conditions of atmospheric phenomena the 

 existence of dust on exposed surfaces is more likely to be a terrestrial 

 than a cosmical phenomenon. 



Chronicles of the progress of astronomical science for the past 

 quarter would not be complete were we to omit to mention that the 

 French Academy of Sciences has awarded the Lalande Medal, the 

 highest astronomical prize in the gift of the Academy, to Mr. Eichard 

 Carrington, of Eedhill, the indefatigable observer of solar spots. This 

 is the greater honour, inasmuch as Anglophobia is by no means rare 

 amongst members of the French Academy. 



