[Footnote 102: The uncertainty affecting the best attainable results in weather-cycle investigation is rendered strikingly apparent by a comparison of the able and laborious papers by H. W. Clough (_Astrophysical Journal_, vol. xxii., p. 42), and C. Easton (Petermann's _Geogr. Mittheilungen_, 1905, Heft VIII., and _Proceedings Amsterdam Academy of Sciences_, June 24, 1905).] [Footnote 103: R. T. A. Innes, _Reference Catalogue_, p. 155A.] [Footnote 104: _Harvard Annals_, vol. liii., p. 61, where, however, the reversal is explained by a shifting of the plane of rotation.] [Footnote 105: G. H. Darwin, _Philosophical Transactions_, vol. clxxii., p. 526; Moulton, _Astrophysical Journal_, vol. xi., p. 110.] [Footnote 106: _Monthly Notices_, vol. ix., p. 91.] [Footnote 107: F. E. Ross, _Lick Bulletin_, No. 82.] [Footnote 108: _Annuaire du Bureau des Longitudes_, 1898.] CHAPTER XV REMNANTS AND SURVIVALS If the sun and planets were, in sober truth, wrought into their present shape out of a primordial nebula, the comparatively void surrounding space should naturally be strewn with fragments of unappropriated material. For the process of englobement could hardly, one would think, be carried out with such neatness and precision as to leave no shreds or shavings lying about the great atelier. Residual stuff there must be, unless our preconceived ideas are grossly erroneous; nor have we far to look in order to find it. We find it, apparently, under two forms presenting curious dissimilarities, yet belonging fundamentally, we can scarcely doubt, to the same order of things. These two kinds of waste product may be identified in the innumerable army of comets and in the strange, pale cone of the zodiacal light.