The evidence from the recent eclipses indicates beyond all possibility of doubt or question, that during the years when sun-spots were numerous, in 1870 and 1871, the corona, at least on the days of the total solar eclipses in those years, presented an appearance entirely different from that of the corona seen on July 29, 1878, when the sun was almost free from spots. This will be more fully indicated further on. At present it is necessary to notice only (1) that whereas in 1870 and 1871 the inner corona extended at least 250,000 miles from the sun, it reached only to a height of some 70,000 miles in 1878; (2) in 1870 and 1871 it possessed a very complicated structure, whereas in 1878 the definite structure could be recognised only in two parts of the inner corona; (3) in 1871 the corona was pink, whereas in 1878 it was pearly white; (4) the corona was ten times brighter in 1871 than in 1878; lastly, in 1871 the light of the corona came in part from glowing gas, whereas in July, 1878, the light came chiefly, if not wholly, from glowing solid or liquid matter. I must here point out, that the evidence of change, however satisfactory in itself, would be quite insufficient to establish the general theory that the corona sympathises with the solar photosphere in the special manner suggested by the recent eclipse observations. There are few practices more unscientific, or more likely to lead to erroneous theorising, than that of basing a general theory on a small number of observations. In this case we have, in fact, but a single observed correspondence, though the observations establishing it form a series. It has been shown that so far as the special sun-spot period from the minimum of 1867 to the minimum of 1878 is concerned, there has been a certain correspondence between the aspect of the corona and the state of the sun's surface, with regard to spots. To assume from that single correspondence that the corona and the sun-spots are related in the same way, would be hazardous in the extreme. We may indeed find, when we consider other matters, that the probability of a general relation of this sort existing is so great antecedently, that but slight direct evidence would be required to establish the existence of the relation. But it must be remembered that before the eclipse of 1878 was observed, with the special result I have noticed, few were bold enough to assert the probable existence of any such relationship; and certainly no one asserted that the probability was very strong. I believe, indeed, that no one spoke more definitely in favour of the theory that the corona probably sympathises with the sun-spots than I did myself before the recent eclipse; but certainly I should not then have been willing to say that I considered the evidence very strong. We must then look for evidence of a more satisfactory kind.