irreconcilable with a swift rate of rotation were
made at Bothkamp in 1871 by Vogel and Lohse;[841] and a drawing executed
by Professor Holden with the great Washington reflector, December 15,
1877, showed the same markings in the positions recorded at Milan to
have been occupied by them eight hours previously. Further, a series of
observations, carried out by M. Perrotin at Nice, May 15 to October 4,
1890, and from Mount Mounier in 1895-6, with the special aim of testing
the inference of synchronous rotation and revolution, proved strongly
corroborative of it.[842] A remarkable collection of drawings made by
Mr. Lowell in 1896 appeared decisive in its favour;[843] Tacchini at
Rome,[844] Mascari at Catania and Etna,[845] Cerulli at Terano,[846]
obtained in 1892-6 evidence similar in purport. On the other hand,
Niesten of Brussels found reason to revert to Vico's discarded elements
for the planet's rotation;[847] and Trouvelot,[848] Stanley
Williams,[849] Villiger,[850] and Leo Brenner,[851] so far agreed with
him as to adopt a period of approximately twenty-four hours. Finally, E.
Von Oppolzer suggested an appeal to the spectroscope;[852] and
Belopolsky secured in 1900[853] spectrograms apparently marked by the
minute displacements corresponding to a rapid rate of axial movement.
But they were avowedly taken only as an experiment, with unsuitable
apparatus; and the desirable verification of their supposed import is
not yet forthcoming. Until it is, Schiaparelli's period of 225 days must
be allowed to hold the field.

Effects attributed to great differences of level in the surface of Venus
have struck many observers. Francesco Fontana at Naples in 1643 noticed
irregularities along the inner edge of the crescent.[854] Lahire in 1700
considered them--regard being had to difference of distance--to be much
more strongly marked than those visible in the moon.[855] Schroeter's
assertions to the same effect, though scouted with some unnecessary
vehemence by Herschel,[856] have since been repeatedly confirmed;
amongst others by Maedler, De Vico, Langdon, who in 1873 saw the broken
line of the terminator with peculiar distinctness through a veil of
auroral cloud;[857] by Denning,[858] March 30, 1881, despite preliminary
impressions to the contrary, as well as by C. V. Zenger at Prague,
January 8, 1883. The great mountain mass, presumed to occasion the
periodical blunting of the southern horn, was precariously estimated by
the Lil