462 



MOUND EXPLORATIONS. 



* North wing. 



t South wing. 



From the plat made according to these figures we ascertain that the 

 longest diameter, namely that running northeast and southwest, is 

 1,189 feet; and the shortest, southeast and northwest, is 1,163 feet; a 

 difference of 20 feet. Although not a true cii'cle, the difference between 

 the longest and shortest diameters falls much short of 100 feet, the 

 difference given by Messrs. Squier and Davis. PI. xxxi shows the cir- 

 cle according to an exact scale ; the dark line along the wall indicating 

 the line of the survey. 



OBSERVATORY CIRCLE. 



This circle, which is marked F on PI. xxv of "Ancient Monuments," 

 is situated at the extreme west of the great group, and is yet very dis- 

 tinct, being about 3 feet high at the lowest point, the average height 

 being between 4 and 5 feet. Most of the south half is yet in the 

 original forest and has never been injured by the plow; but the 

 north half has been under cultivation for a number of years and is 

 considerably worn. The effect of this wearing is apparent not only iu 

 the decrease in height, but in the increase in width, of this portion of 

 the wall as shown by the field notes given below. The field notes are 

 as follows, beginning at station 0, in the midille of the gateway leading 

 to the octagon : 



