idence; nor can
we be certain, until it is seen, that we have really got into touch with
it.

FOOTNOTES:

[Footnote 965: _Phil. Trans._, vol. lxxiv., p. 260.]

[Footnote 966: _Novae Observationes_, p. 105.]

[Footnote 967: _Phil. Trans._, vol. i., p. 243.]

[Footnote 968: _Mem. de l'Ac._, 1720, p. 146.]

[Footnote 969: _Phil. Trans._, vol. lxxiv., p. 273.]

[Footnote 970: A large work, entitled _Areographische Fragmente_, in
which Schroeter embodied the results of his labours on Mars, 1785-1803,
narrowly escaped the conflagration of 1813, and was published at Leyden
in 1881.]

[Footnote 971: _Beitraege_, p. 124.]

[Footnote 972: _Mem. R. A. Soc._, vol. xxxii., p. 183.]

[Footnote 973: _Astr. Nach._, No. 1,468.]

[Footnote 974: _Observatory_, vol. viii., p. 437.]

[Footnote 975: _Month. Not._, vols. xxviii., p. 37; xxix., p. 232;
xxxiii., p. 552.]

[Footnote 976: Flammarion, _L'Astronomie_, t. i., p. 266.]

[Footnote 977: Smyth, _Cel. Cycle_, vol. i., p. 148 (1st ed.).]

[Footnote 978: _Phil. Trans._, vol. cxxi., p. 417.]

[Footnote 979: _Month. Not._, vol. xxv., p. 227.]

[Footnote 980: _Phil. Mag._, vol. xxxiv., p. 75.]

[Footnote 981: Proctor, _Quart. Jour. of Science_, vol. x., p. 185;
Maunder, _Sunday Mag._, January, February, March, 1882; Campbell, _Publ.
Astr. Pac. Soc._, vol. vi., p. 273.]

[Footnote 982: _Am. Jour. of Sc._, vol. xxviii., p. 163.]

[Footnote 983: Burton, _Trans. Roy. Dublin Soc._, vol. i., 1880, p.
169.]

[Footnote 984: _Month. Not._, vol. xxvii., p. 179; _Astroph. Journ._,
vol. i., p. 193.]

[Footnote 985: _Untersuchungen ueber die Spectra der Planeten_, p. 20;
_Astroph. Journ._, vol. i., p. 203.]

[Footnote 986: _Publ. Astr. Pac. Soc._, vols. vi., p. 228; ix., p. 109;
_Astr. and Astroph._, vol. xiii., p. 752; _Astroph. Jour._, vol. ii., p.
28.]

[Footnote 987: _Ibid._, vol. v., p. 328.]

[Footnote 988: _Ibid._, vols. i., p. 311; iii., p. 254.]

[Footnote 989: C. Christiansen, _Beiblaetter_, 1886, p. 532.]

[Footnote 990: _Astr. and Astrophysics_, vol. xi., p. 671.]

[Footnote 991: Flammarion, _La Planete Mars_, p. 574.]

[Footnote 992: _Memoires Couronnes_, t. xxxix.]

[Footnote 993: Lockyer, _Nature_, vol. xlvi., p. 447.]

[Footnote 994: _Mem. Spettr. Italiani_, t. xi., p. 28.]

[Footnote 995: _Bull. Astr._, t. iii., p. 324.]

[Footnote 996: _Journ. Brit. Astr. Ass._, vol. i., p. 88.]

[Footnote 997: _Publ. Pac. Astr. Soc._, vol. ii., p. 299; Perci