308 SCIENTIFIC RECORD FOR 1882. 



June, 1750, and these are reproduced by photoheliograpLy, so that tlie 

 ■copies are faithful representations of the originals. They are accompa- 

 nied by a copy of Mayer's large general map, of nearly fourteen inches 

 diameter; and thus the results of his old selenographical observations, 

 obtained with humble means, have at last become available, and a debt 

 long due to him has been paid by the Gottingen observatory. 



Mr. Henry Harrison, of New York, has published a colored lithograph 

 Tepresenting the moon as the " three-days-old crescent," or as it appears 

 three days after the time of new moon. As the ordinary lunar maps 

 are constructed with the object of exhibiting the general topograyjhy of 

 the whole visible surface, they do not represent, and are not intended 

 to represent, the real aspect of the moon at any time; and it is necessary 

 to have special maps for special phases of illumination if they are to 

 show the shadows and other variable features which are so strikingly 

 ■characteristic of the moon's appearance at different hours of the lunar 

 ■day. Mr. Harrison's lithograph is such a special representation, and, 

 as regards general resemblance and artistic effect, may be called a suc- 

 •cess. Though it does not show more than a small portion of the in- 

 numerable details which the telescoi^e reveals, it gives a good notion 

 •of the telescopic appearance of the young moon as seen with a com- 

 paratively^ low power. The moon's image is eighteen inches in diameter, 

 the phase represented corresponding to the time when the crater Messier 

 has emerged into the light of the rising sun. 



The plate is accompanied by a little descriptive hand-book and an 

 outline map. Its publication will be followed by that of five more plates 

 containing similar representations of five of the most interesting phases. 



Experiments have repeatedly been made with the object of produc- 

 ing natural imitations of the craters and inequalities visible on the 

 moon's surface, and it has been found that the figures of the lunar in- 

 equalities can be closely imitated by throwing pebbles upon the surface 

 of a smooth, plastic mass such as mud or mortar. Mr. Meydeubauer, 

 of Marburg, uses a basis of dextrine for the purpose and drops small 

 quantities of the same material from a moderate height upon that basis. 

 A photograph of various figures which are thus produced show a re- 

 markable resemblance to the various inequalities visible on the moon's 

 surface. (A. Marth, in the London Academy.) 



The topography of the planet Mars. — Professor Schiaparelli has pub- 

 lished a second important memoir, entitled " Osservazioni Astronomiche 

 e Fisiche sull' Asse di Eotazione e sulla Topografia del Pianeta Marte 

 - - -." (Reale Accademia dei Idncei, anno cclxxviii, 1880-'81,) By 

 combining his observations at the oppdsition 1879-'80 with those made 

 at the favorable opposition of 1877, he finds the position of the equa- 

 tor of Mars referred to the earth's equator as follows : Ascending node 

 (1880), in 480 7' .8 inclination 36° 22' .9— figures differing little from 

 those provisionally adopted by Mr. Marth. 



