ny spots visible on the disc cross it in apparently
straight lines. At other times, the paths pursued by them seem
curved--downward (to an observer in the northern hemisphere) between
June and December, upward between December and June.

A singular peculiarity in the distribution of sun-spots emerged from
Carrington's studies at the time of the minimum of 1856. Two broad belts
of the solar surface, as we have seen, are frequented by them, of which
the limits may be put at 6 deg. and 35 deg. of north and south latitude.
Individual equatorial spots are not uncommon, but nearer to the poles
than 35 deg. they are a rare exception. Carrington observed--as an extreme
instance--in July, 1858, one in south latitude 44 deg.; and Peters, in June,
1846, watched, during several days, a spot in 50 deg. 24' north latitude.
But beyond this no true macula has ever been seen; for Lahire's reported
observation of one in latitude 70 deg. is now believed to have had its
place on the solar globe erroneously assigned; and the "veiled spots"
described by Trouvelot in 1875[423] as occurring within 10 deg. of the pole
can only be regarded as, at the most, the same kind of disturbance in an
undeveloped form.

But the novelty of Carrington's observations consisted in the detection
of certain changes in distribution concurrent with the progress of the
eleven-year period. As the minimum approached, the spot-zones contracted
towards the equator, and there finally vanished; then, as if by a fresh
impulse, spots suddenly reappeared in high latitude, and spread
downwards with the development of the new phase of activity. Scarcely
had this remark been made public,[424] when Wolf[425] found a
confirmation of its general truth in Boehm's observations during the
years 1833-36; and a perfectly similar behaviour was noted both by
Spoerer and Secchi at the minimum epoch of 1867. The ensuing period gave
corresponding indications; and it may now be looked upon as established
that the spot-zones close in towards the equator with the advance of
each cycle, their activity culminating, as a rule, in a mean latitude of
about 16 deg., and expiring when it is reduced to 6 deg. Before this
happens, however, a completely new disturbance will have manifested itself
some 35 deg. north and south of the equator, and will have begun to travel
over the same course as its predecessor. Each series of sun-spots is thus,
to some extent, overlapped by the succeeding one; so that w