194 The Moon. 



reflector, will be a little puzzling at first, and should be tho- 

 roughly mastered in order not to get bewildered and lose our 

 way in following the description of details. 



"We are now prepared to enter upon an individual examina- 

 tion of the most conspicuous wonders of our satellite ; a few 

 preliminary remarks, however, may be expedient, to put the 

 student in possession of such information as he may subse- 

 quently find useful. With regard to the lunar nomenclature, 

 this, though now reduced to a settled arrangement, has been 

 formerly subject to great variation. Hevel, the celebrated 

 observer of Dantzig, who flourished during the latter half of 

 the seventeenth century, was the first to designate the various 

 regions and spots by names ; these he derived from some kind 

 of analogy between the configurations of the terrestrial and 

 lunar surfaces — occasionally a tolerably happy one, but gene- 

 rally speaking very inappropriate, as well as inadequate to meet 

 the future requirements of advancing knowledge. His suc- 

 cessor, Riccioli, though an inferior observer, improved con- 

 siderably upon this method, by the adoption of Hevel's earlier 

 idea, which had been abandoned from the fear of apparent 

 partiality, and which consisted in the employment of the 

 names of eminent scientific men — among these taking care not 

 to forget Ms own. He changed, at the same time, Hevel' s 

 appellations of the so-called seas, for others referring to sup- 

 posed influences exercised by the moon upon the atmosphere 

 and productions of the earth, and altered in a similar way those 

 of the higher districts and mountain ranges ; but in the latter 

 case his designations have fallen into disuse, or have, in a few 

 instances, been unable to supplant the earlier ones. Fortu- 

 nately for Riccioli's scheme, it is of an elastic character; the 

 (•(instant increase in the number of scientific names admitting 

 of its extended application in proportion to the increased 

 number of spots which modern accuracy seeks to distinguish ; 

 such an extension is, in fact, being carried onf at the present 

 time by OUT Own zealous and able selenographer, Mr. Birt ; 

 and this nomenclature may now be considered as established 

 beyond the prosped of change. As, however, it would bo 

 obviously impossible to find separate designations in this way 

 for all the objects which require to be Identified, Sohrfiter 



introduced the use of the letters of the Roman and (ireek 



alphabets for the minor details in each of his " selenotopo- 



graphical" plates ; and this plan has been reduced by ] Jeer and 



Miidler to a regular system, which it may be desirable to ex- 

 plain in this place, as their letter-press is not always in the 

 hands of the possessors of their map. Every object which has 

 no proper name is referred to the nearest spot so designated; 

 if a mountain, it is indicated by a Greek, if a hollow, by a Latin 



