The opinion of the Kew observers as to the nature of such disturbances was strongly swayed by another curious result of the "statistical method" of inquiry. They found that of 1,137 instances of spots accompanied by faculæ, 584 had those faculæ chiefly or entirely on the left, 508 showed a nearly equal distribution, while 45 only had faculous appendages mainly on the right side.[455] Now the rotation of the sun, as we see it, is performed from left to right; so that the marked tendency of the faculæ was a lagging one. This was easily accounted for by supposing the matter composing them to have been flung upwards from a considerable depth, whence it would reach the surface with the lesser _absolute_ velocity belonging to a smaller circle of revolution, and would consequently fall behind the cavities or "spots" formed by its abstraction. An attempt, it is true, made by M. Wilsing at Potsdam in 1888[456] to determine the solar rotation from photographs of faculæ had an outcome inconsistent with this view of their origin. They unexpectedly gave a uniform period. No trace of the retardation poleward from the equator, shown by the spots, could be detected in their movements. But the experiment was obviously inconclusive;[457] and M. Stratonoff's[458] repetition of it with ampler materials gave a full assurance that faculæ rotate like spots in periods lengthening as latitude augments. The ideas of M. Faye were, on two fundamental points, contradicated by the Kew investigators. He held spots to be regions of _uprush_ and of heightened temperature; they believed their obscurity to be due to a _downrush_ of comparatively cool vapours. Now M. Chacornac, observing, at Ville-Urbanne, March 6, 1865, saw floods of photospheric matter visibly precipitating themselves into the abyss opened by a great spot, and carrying with them small neighbouring maculæ.[459] Similar instances were repeatedly noted by Father Secchi, who considered the existence of a kind of _suction_ in spots to be quite beyond question.[460] The tendency in their vicinity, to put it otherwise, is _centripetal_, not _centrifugal_; and this alone seems to negative the supposition of a central uprush.