1902.] LOWELL — AREOGRAPHY. 225 



AREOGRAPHY. 



BY PERCIVAL LOWELL. 

 (^Read April J^, 1902.) 



1. Facts familiar to the specialist are often credited with a gen- 

 eral appreciation they do not possess. Immersed in his own line 

 of research, the investigator forgets that others are not as intimate 

 as he with some of the fundamental points of his inquiry, and 

 omits as truisms what to others are not even known for truths. 

 Areography is such a subject. Probably no one outside of the pur- 

 suit is aware how cogent is the conclusion to be derived from an 

 inspection of the maps that have been made of the planet, as to 

 the reality and the relation of the markings there depicted. Nor 

 was it indeed till after I had compared these maps with some par- 

 ticularity that certain deductions from them forced themselves upon 

 me. It will perhaps, therefore, not be unproductive of result if I 

 present at this general meeting a collective view of the maps which 

 have from time to time been made of Mars and note what they 

 imply. Maps speak best for themselves, and with very slight intro- 

 duction can be made to tell their own story better than any amount 

 of text. 



2. Of the maps here brought together, the earlier are taken 

 from Flammarion's thesaurus La Planete Mars^ Proctor's Dawes' 

 map from his own book, Schiaparelli's from his memoirs in the 

 Accademia dei Lincei, and the later ones from my own work. Of 

 these latter, that for 1896-97 is the result of my own synthesis of 

 the Flagstaff and Mexican observations of the Lowell Observatory 

 for those years, while the ones for 1898-99 and 1900-01 I have 

 but just completed, and they appear here for the first time. 



3. All the maps here given marked in their day the point that 

 areography had then reached. With but two exceptions, that of 

 Flammarion and Proctor, therefore, they represent original obser- 

 vations made by the maker of the map himself or under his direc- 

 tion, and show in procession the evolutionary development of the 

 subject. Such maps as failed to add to existing knowledge and are 

 valuable merely as confirmatory documents have not been included. 

 On the other hand, no map which materially contributed anything 

 has been left out. Many excellent charts, therefore, have had to 

 be omitted, not always because they presented nothing new, but 



