188 [Assembly 



believing that a more acceptable service could not be rendered to 

 the building and economic interests of the State ; and the New 

 Capitol Commissioners have an opportunity of rendering this service 

 to the general welfare of the community, while fortifying themselves 

 with all available information to govern their own action in. the 

 selection of materials, not only for the exterior walls, but for interior 

 use and decoration. 



For the latter object, I would very earnestly recommend that 

 specimens from all formations yielding marble, or of limestone bear- 

 ing a good polish, be used in some part of the New Capitol work. 

 With this object in view, I have already procured specimens of some 

 of these stones, but the collection in this department is scarcely 

 begun. 



i have already recommended to you certain localities from which 

 foundation stones may be obtained. In this statement, I think I 

 omitted, or did not definitely specify, the locality of gneiss or 

 granite in the Highlands on the Hudson river, of which the quar- 

 ries at Breakneck and Butter hill offer good examples. 



As a preliminary to our inquiries after proper hidlding stone, we 

 may first consider what are the materials with which we have to 

 deal. The rocks or varieties of rocks offered in nature, and from 

 which we are compelled to make our selections, may be named 

 under the following heads : 



1. Granites, including Sienite, Gneiss, etc. 



2. ^Iarbles, or Meta.morphic crystalline limestones. 



3. Limestones, not metamorj>hic, compact or siLbcrystalline. 



4. Sandstones or Freestones, and their varieties resulting from admixture 



of clay or carbonate of lime, etc. 



In the first place, it should be understood that under each of these 

 heads there is an almost infinite variety in texture, color, power of 

 resistance Xo irressure, duraVility , etc. ; that the substances named 

 are very widely distributed, and that they vary in different and dis- 

 tant localities ; that a sandstone is rarely a purely siliceous rock, or 

 a limestone a purely calcareous or calcareo-magnesian rock ; other 

 materials foreign to their strict constitution, according to the usual 

 designation, enter into their composition, and, for the most part, to 

 the injury of the mass. In the purely sedimentary rocks, which 

 have undergone no subsequent change, the sandstones are more or 

 less permeated by argillaceous matter or clay, which constituted a 

 part of the original sediment, and which may be uniformly mingled 

 throughout the entire mass, or may form thin layers or seams 

 separating the harder layers. In either case it is a dangerous 

 ingredient ; for no rock with clay seams can long be exposed to the 

 weather, without a greater or less degree of separation or disintegra- 

 tion ; and when au}^ considerable amount of the same material is 

 distributed through the mass, its ready absorption of water renders 

 it equally dangerous to the stability and integrity of the whole. 

 Placed beneath the surface, and beyond the reach of frosts, the con- 

 ditions are different, and such rocks last for an indefinite period of 

 time. 



