great craters, forming ray-centres.
(2.) Speaking generally, a very minute and brilliant crater is located at
the end of the streak nearest the radiant point, the streak spreading out
and becoming fainter towards the other end. The majority of the streaks
appear to issue from one or more of these minute craters, which rarely
exceed a mile in diameter.
(3.) The streaks which do not issue from minute craters, usually lie upon
or across ridges, or in other similar exposed situations, sometimes
apparently coming through notches in the mountain walls.
(4.) Many of the Copernicus streaks start from craterlets within the rim,
flow up the inside and down the outside of the walls. Kepler includes two
such craterlets, but here the flow seems to have been more uniform over
the edges of the whole crater, and is not distinctly divided up into
separate streams.
(5.) Though there are similar craters within Tycho, the streaks from them
do not extend far beyond the walls. All the conspicuous Tycho streaks
originate outside the rim.
(6.) The streaks of Copernicus, Kepler, and Aristarchus are greyish in
colour, and much less white than those associated with Tycho: some white
lines extending south-east from Aristarchus do not apparently belong to
the system. In the case of craterlets lying between Aristarchus and
Copernicus the streaks point away from the latter.
(7.) There are no very long streaks; they vary from ten to fifty miles in
length, and are rarely more than a quarter of a mile broad at the crater.
From this point they gradually widen out and become fainter. Their width,
however, at the end farthest from the crater, seldom exceeds five miles.

These statements, especially those relating to the length of the streaks,
are utterly opposed to prevailing notions, but Professor Pickering
specifies the case of the two familiar parallel rays extending from the
north-east of Tycho to the region east of Bullialdus. His observations
show that these streaks, originating at a number of little craters
situated from thirty to sixty miles beyond the confines of Tycho, "enter
a couple of broad slightly depressed valleys. In these valleys are found
numerous minute craters of the kind above described, with intensely
brilliant interiors. When the streaks issuing from those craters near
Tycho are nearly exhausted, they are reinforced by streaks from other
craters which they encounter upon the way, the streaks becoming more
pronounced at these points