‘ 
a 6 Experiments on American and Foreign Building Stones. 
_ perior hardness left slightly elevated above the surface of the 
_ bonate of lime which is worn away in ng. 
«The surface of polished stone thus variously marked with ele-— 
es vations and cavities, may be used like an engraver’s plate, and 
will give an impression of its own markings, of much interest. 
1. Trials of two-inch cubes of the coarse-grained “ alum 
” limestone,” used at the National Washington Monument, to as- | 
certain its resistance to crushing. By Dr. Charles G. Page— 
The specimens were stated to have been furnished by the owner 
of he: quarries, and the testing to have been performed by the 
aid of a “powerful hydraulic press,” so arranged as to “ indicate 
accurately the amount of pressure.” Not having witnessed any 
of the experiments or the arrangements of the machine, the — 
writer feels bound to say that these allegations respecting the 
i machine have been published by the architect, by the superin- 
_~ tendent, and by others concerned in building the monument at 
Washington. ‘a experiments were communicated to the 
writer by Dr. P 
a = No. of the trial. Crushing weight in pounds per square inch. 
ewe : : : ‘ : soe. SAU | 
ae 2. : : : ‘ ; : 1372 ee 
we , 7 -. ee ee oe 
4 ‘ : 2312 
5 2437 
6 ; 2531 
7 diseaedt . z : ; 2625 
8. ; : ‘ ; : . 2650 
: 9 . Sal 2750 
10 ‘ . 2843 
il ‘ : : 2968 
Average Say ‘ ; ; 2334 
‘Note.—From the above it appears that the greatest strength 
per square inch, when tested in two inch cubes is 2968 pounds, | 
and the least 910 pounds, the latter being about 30 per cent. of 
the far number. 
. Lrials by Dr. Page, of other building materials to obtain 
results, o n two-inch cubes, comparable with those afforded b 2 
the idan limestone.” ‘ 
: No. of trial. ape 
1. Fine- rained tare of Sineineti ‘ . 4562 
2. Moot ple do. 
3. White sora seachle: East ——. N. Y, used 
at the General Post Office 
. do. ers Regen : ; : 
~ Ttalian marb cc: ? i 
