126 THE AMERICAN BEAYER. 



tion of seventy feet was to be taken by turning the 

 instrument to the left, without changing its focal 

 position, as clone in the previous case. This would 

 give to the seven plates a lineal length of three hun- 

 dred and ninety feet, and an actual length of dam, 

 measured upon its sinuous crest, of four hundred and 

 twenty-six feet. The dam, for the last-named length, 

 is shown in the plates, with the background of the 

 pond and surrounding forest three times repeated in 

 the three central plates. Besides this, however, a 

 portion of the dam sixty-two feet long is not shown. 

 "When the dam had approached within six feet of the 

 bank on the left side, it turned directly down stream 

 parallel with it, and was extended for the distance 

 last named, when it finally terminated in the bank; 

 thus forming a narrow canal which followed the dam 

 down to its extreme end. The point where it turns 

 is concealed from view by a clump of cedar-trees 

 which are seen in the left end of the plate. Two 

 days were expended by this advance party in cutting 

 out the several lines, establishing the stations, and in 

 making a commencement of the work. 



On Tuesday, the 30th day of September, 1862, with 

 the instrument and chemicals packed in boxes, we 

 went up the railroad from Marquette to the Superior 

 Mine, where we organized and provisioned our party 

 for an encampment of several days at the dam, some 

 six miles distant. The next day proved unfavorable, 

 with mist and rain, but we reached our destination 

 without accident to the materials, erected two brush- 

 camps, framed and put together a movable scaflbld 

 twelve feet high, with a ladder to mount it, and 

 finished clearing away the area in front of the first 



