184 Sloan's Architectural Review and Builders' Journal. [Sept, The quarry measures 120 feet long by 60 feet in width, and in deptli 100 feet, being 75 feet below the water level. There are two distinct veins, running fromN E. to S. W., dipping at an angle of about 45 degrees, lying in beds of from 8 to 12 feet in thickness, to the depth of 50 or 60 feet. Below that depth, the marble occurs, seemingly, in a solid mass, requiring side picking to get out blocks, which can thus be pro- cured of almost any size. The North vein is 30 feet in width, is of a pale bluish white ; the other, lying south, and separated by a narrow strip of limestone, being in width 26 feet, is nearly pure white, with a faint bluish tinge. The rock stratification at this place is quite an interesting geological study ; there having been a seeming upheaval, covering an area of some 6 to 8 acres, 20 to 22 feet above the sur- rounding surface, the mound, or plateau, being composed of different shades of marble, from dark blue and black to nearly pure white, .in alternate veins. South of this manifestation and lying on, and contiguous to, the black, is found a considerable deposit of Hematite, or sesqui-oxide of iron, with large masses of a bluish clay, containing plumbago in small quantities, running into the slate, which bounds the Chester valley on the south. These quarries were worked, success- fully, for eleven years, or, until the completion of the College, in 1844, during which time were built — the Preston Retreat, on Hamilton street, a Lying-in-Hospital, now in a flourishing . condition, and fully carrying out the designs of its benevolent founder, — the noble mansion of the late Matthew Newkirk, Esq., at the corner of Thir- teenth and Arch streets, and the classic edifice in West Chester, Chester county, erected in 1836, under the superinten- dence of Thomas U. Walter, Esq.,* by
- Architect of Giiard College ; aud of the extension of
the Capitol at Washington, D. 0. the Bank of Chester county, now the National Bank of Chester county. The last-named edifice is perhaps the most beautiful and correct specimen of the Grecian Doric in the United States, being an exact copy of the Agora, at Athens ; and is now in as perfect state of preservation as when first built. Indeed the stone stands the exposure of years without the least appearance of crumbling:, or disintegration ; and re- tains its color perfectly, without stain or blemish, proving that our changeable climate, with its extremes of temper- ature, does not in the least affect it. That it does affect much of the marble and other kinds of stone in this country, is demonstrated by many of our build- ings. The facts are, that its analysis shows no Talc, and but little earthy matter ; that it is composed of neai'ly pure carbonate of lime, with considerable silex ; and that, although hard to work, it finishes smoothly. These character- istics render it more enduring for monumental purposes. The specimens in our cemeteries here, as well as through the South, prove it well adapted for necropolitan adornment. Abandoned, on account of the diffi- culty and cost of sizing the blocks, and of getting the marble to market — there being neither railroad facilities, nor the means of sawing as at present — the quarry lay dormant for twenty-three years, till, in March, 1861, it was re- opened by the Messrs. Thomas,* who have made a connection with the Chester Valley Railroad ; and having erected a mill, with ample steam-power, can, by working both veins, supply to stone- cutters and builders the different kinds of stock it affords, with equal facility and promptitude. The dark blue marble shows to much advantage, in the rural districts ; is well adapted to villas, near cities, and
- J. Preston Thomas and George Thomas, Jr., opera-
ting as Thomas Brothers, West Whiteland P. O., Chester county, Pennsylvania.
