. PHYSICAL ASTRONOMY. 133 
discovery. He seems to have exhibited, in May, 1611, the first spot to his 
pupils in Ingolstadt, where he was professor. Galileo had observed the spots 
of the sun as early as the beginning of 1611, nearly contemporaneously with 
Fabricius, and very soon presented correct views of their nature. 
Topography of the Moon. 
52. The most interesting object visible by a good telescope in the 
heavens, is certainly the surface of the moon, whose peculiarities, as being 
of all heavenly bodies the nearest to us, are known best of all. At an early 
period Galileo, Scheiner, and Hevelius, and afterwards Grimaldi, Riccioli, 
Cassini, and Lahire, attempted to construct a chart of the moon; the maps 
of the moon by Hevelius, Mayer, and Schroter, are well known. Lohrmann, 
however, uniting an intimate knowledge of facts with sound judgment, first 
published accurate and beautiful maps of the moon, four in number, whose 
continuation was unfortunately arrested by his death. Beer and Madler, 
finally, in 1836, published four large sheets with a general map of the moon, 
on Lohrmann’s plan, indeed, but founded on original observations. Of this 
general map pl. 11, fig. 1 is an accurately reduced copy. Our chart repre- 
sents the moon inverted, or as it would be exhibited to the observer in an 
astronomical telescope of from 60 to 80 magnifying power. North is con- 
sequently below, South above, East to the right, and West to the left. 
From want of room, and to avoid crowding, the single mountains and 
craters are indicated by numbers, whose import will presently be explained. 
On the moon there can be directly distinguished nothing but differences of 
level and illumination; consequently only mountains, craters, and colors. 
The two first are exhibited best in the growing and waning moon, when the 
part to be observed lies near the illuminated border; the colors we see to 
the most advantage at the full moon. Many of the ring mountains have, | 
following Riccioli’s example, been named after eminent philosophers ; while 
for the rest, with Hevelius, the names of mountains, rivers, &c., have been 
borrowed from the earth. 
53. The numbers annexed to the names in the following list, indicate 
the depth or the inner descent of the wall in Paris feet ; where a second num- 
ber, inclosed in brackets, occurs, it indicates the height of the wall above the 
outer inclosure. All these numbers are derived from original measure- 
ments by Beer and Madler. 
133 
