THE GREAT EXHIBITION BUILDINGS. 
325 
them at any time during the Exhibition. The results of these experi- 
ments fully bear out our calculations on the strength of the different parts of 
the structure, and we feel perfectly satisfied as to the stability of the building 
for the purpose for which it was intended. 
“ The two large domes, in the strength of which we have taken great 
interest, were eased from their temporary support last week, and no observable 
settlement took place. 
“ The following are the particulars of the tests : — The first caused a large 
body of men, about 400 in number, to be closely packed upon a space 25 feet 
by 25 feet, on one bay of flooring ; we then moved them in step, and after- 
wards made them run over the different galleries, and down each staircase ; 
at the same time we caused the deflections of the girders carrying these floors 
to be carefully noted at several places, and had the satisfaction of finding 
that in each case the deflections were very nearly the same, thus exhibiting a 
remarkable uniformity in the construction. The caskiron girders, with 25 feet 
bearings, deflected only one-eighth of an inch at the centre, and the timber- 
trussed beams of the same bearing placed between these girders deflected 
half an inch at the centre. In every instance the girders and trusses recovered 
their original position immediately on the removal of the load. 
“We are, my Lords and Gentlemen, yours faithfully, 
“ WM. FAIRBAIRN, ) 
“London, Feb. 13.” “ WILLIAM BAKER, 1°' ' 
Before the dimensions, forms, and conditions of the columns, 
girders, trussed beams, and rafters had been decided upon, a 
long series of preliminary experiments were carried on, and it 
was not until the Building Committee and Captain Fowke were 
fully satisfied as to the security of every part, that the building 
was allowed to proceed. Not satisfied with these early pre- 
cautions, the Building Committee resorted to the final and still 
more severe tests of impact and concussion as produced by 
marching the large body of men linked together over stairs 
and galleries at quick and afterwards at “ double step/'’ 
stamping hard on every part of the bays of 25 feet square. 
All these precautions have been taken to secure the public 
safety when placed under every conceivable condition in which 
they can be loaded by a moving mass of people. 
Amongst the most prominent features of these buildings, and 
those that have created anxious consideration on the part of the 
Building Committee and the engineer, Mr. Meeson, are the great 
Domes. These large constructions (designed on a scale greater 
than anything of the kind had ever been done before) were 
carefully considered, in order to be within the limits of the 
estimates, and at the same time to ensure ample stability in 
the structures. They were originally calculated to sustain a 
force of 40 lb. per square foot, if such a force could ever be 
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