378 
THOMAS LINCOLN CASEY. 
masonry, and the known weakness of the foundation, all ren¬ 
dering operations on it exceedingly delicate, were most serious 
elements in the case. What sort of strengthening was needed 
and how to execute it safely were the questions. The problem 
was at once attacked with characteristic vigor and energy by 
Colonel Casey. Night and day for a few weeks the subject 
was studied and plans of operations devised, and in the amaz¬ 
ingly short space of one month from the day he took charge 
an original project was prepared and submitted to the joint 
commission, which immediately approved it. The work was 
undertaken as soon as materials and machinery could be 
procured, and the extremely delicate operation of underpin¬ 
ning and buttressing with concrete a foundation carrying 
some 35,000 tons on an earth bed yielding under its enormous 
load at every touch was successfully accomplished in less than 
a year and a half. The structure naturally moved somewhat 
during the operations, leaning slightly one way and another 
as the inevitable slight settlements took place, but the alge¬ 
braic sum of these movements was zero, and the total settle¬ 
ment of the center of gravity only about 2J inches. The 
performance of this w T ork properly gained for its engineer a 
world-wide reputation, particularly in the profession of civil 
engineering, but the special problems of the completion of 
the whole monument had not all been solved in the founda¬ 
tion. The construction of the shaft proper was a compara¬ 
tively simple matter, but its walls were necessarily made as 
thin as possible to reduce to a minimum the load on the 
foundation, and this led to the unique problem of placing, 
without the use of metal, a stone apex or pyramidion, 55 feet 
in height, on the 18-inch edge of the four walls of the square 
shaft, whose sides were 34 feet 5J inches in length, at 500 feet 
above the ground. This square was entirely hollow, without 
cross-ties of any kind. The design and execution of this por¬ 
tion of the monument was also expeditiously accomplished, 
and on December 6, 1884, Colonel Casey himself set the cap¬ 
stone, amid the cheers of the people and the salute of cannon, 
and the monument was successfully finished, six years after 
