the eighteenth century, appears not to have seen
any conspicuous crater in the place, though it must be admitted that
his observations are rather incomplete. To give some idea of Schmidt's
amazing industry in lunar researches, it may be mentioned that in six
years he made nearly 57,000 individual settings of his micrometer in the
measurement of lunar altitudes. His great chart of the mountains in the
moon is based on no less than 2,731 drawings and sketches, if those are
counted twice that may have been used for two divisions of the map.

3. _Aristotle._--This great philosopher's name has been attached to a
grand crater 50 miles in diameter, the interior of which, although very
hilly, shows no decidedly marked central cone. But the lofty wall of the
crater, exceeding 10,500 feet in height, overshadows the floor so
continuously that its features are never seen to advantage.

4. _The Great Valley of the Alps._--A wonderfully straight valley, with
a width ranging from 3-1/2 to 6 miles, runs right through the lunar
Alps. It is, according to Maedler, at least 11,500 feet deep, and over 80
miles in length. A few low ridges which are parallel to the sides of the
valley may possibly be the result of landslips.

5. _Aristillus._--Under favourable conditions Lord Rosse's great
telescope has shown the exterior of this magnificent crater to be scored
with deep gullies radiating from its centre. Aristillus is about 34
miles wide and 10,000 feet in depth.

6. _Autolycus_ is somewhat smaller than the foregoing, to which it forms
a companion in accordance with what Maedler thought a well-defined
relation amongst lunar craters, by which they frequently occurred in
pairs, with the smaller one more usually to the south. Towards the edge
this arrangement is generally rather apparent than real, and is merely a
result of foreshortening.

7. _Archimedes._--This large plain, about 50 miles in diameter, has its
vast smooth interior divided by unequally bright streaks into seven
distinct zones, running east and west. There is no central mountain or
other obvious internal sign of former activity, but its irregular wall
rises into abrupt towers, and is marked outside by decided terraces.

[Illustration: PLATE B.

PORTION OF THE MOON.

(ALPS, ARCHIMEDES, APENNINES.)

_Messrs. Loewy & Puiseux_.]

8. _Plato._--We have already referred to this extensive circular plain,
which is noticeable with the smallest telescope. The average height of