NATIONAL MUSEUM BUILDINGS. 197 



somewhat coarse, liiohly crystalline, and inferior in quality, known as 

 "alnni liniestono." 



The quarries in the neiohborhood of AN'oodstock, Mar3'land, fur- 

 nished a granite equal to that of Quincy, and not excelled for beauty 

 of appearance, compactness of structure, and uniformity of color, 

 texture, and composition by any other granite quarries in the United 

 States. There was no objection to this stone except on the score of 

 expense, unless it be considered that in this material the effect of lioht 

 and shade from projecting surfaces is in a measure lost, while in marble 

 and good tinted freestone ever}'^ shadow is sharply marked. 



The Aquia Creek freestone was not to be trusted, ])eing pervaded 

 b}' dark specks of the protoxide and peroxide of iron, which, in per- 

 oxidating, acquire a yellowish or reddish color, and hav^ing occasional 

 clay holes, such as disfigure the Treasury and Patent Office ))uildings. 



The freestone from the upper Potomac, in the vicinity of Seneca 

 Creek, was considered the best and most durable of all the Potomac 

 freestones. The lilac-gray variety found in the Bull Run quarrv, 23 

 miles from Washington, was especially recommended and pronounced 

 to be equal, if not superior, to that supplied for Trinity Church, New 

 York, from the quarries of New Jerse3\ It has a quality that specially 

 recommends it to builders. When first quarried it is comparatively 

 soft, working freely before the chisel and hammer; but, by exposure, 

 it gradually indurates, and ultimatelv acquires a toughness and con- 

 sistency that not only enables it to resist atmospheric vicissitudes, 

 but even the most severe mechanical wear and tear. It can, there- 

 fore, be worked at less expense than granite or marble and was the kind 

 selected for the building. 



All of the above varieties of stone were subjected to tests for dura- 

 bility under exposure to the weather, etc., by Prof. Charles G. Page. 

 Their cost per cubic foot, delivered in Washington, in accordance 

 with the lowest prices quoted b}^ quarry owners, was as follows: 



Cents. 

 L Coarse-grained marble or alum limestone, according to quality 50 to 60 



2. Fine-grained marble 70 



3. Granite 46 



4. Aquia Creek freestone 40 



5. Seneca Creek freestone, lilac-gray variety, from Bull Run quarry 20 



Bids for the construction of the building were received up to March 

 15, 1817, and were opened on March IH. Several were found to be 

 proposals for doing oidy a part or some jiarticular kind of the work, 

 l)ut for the erection oF the entire building there were fourteen bids, 

 varying in amount fiom $IVM;.()0(» to $818,000. James Dixon t'c Co., 

 of Washington, were tli(> lowest bidders for S(Mieca freestone laid in 

 rubble masonry, and also for ashlar finish, as follows: 



Marble ashlar $228, 500 



Seneca freestone ashlar 205, 250 



