<P> Until it was removed, the original lightning protection system was connected to the tops of the four iron columns supporting the elevator with large copper rods . Even though the aluminum apex is still connected to the columns with large copper rods, it is no longer part of the lightning protection system because it is now disconnected from the present lightning rods which shield it . The two lightning rods present since 2013 are connected to the iron columns with two large braided aluminum cables leading down the surface of the pyramidion near its southeast and northwest corners . They enter the pyramidion at its base, where they are tied together (electrically shorted) via large braided aluminum cables encircling the pyramidion two feet (0.6 m) above its base . The bottom of the iron columns are connected to ground water below the monument via four large copper rods that pass through a 2 - foot (0.6 m) square well half filled with sand in the center of the foundation . The effectiveness of the lightning protection system has not been affected by a significant draw down of the water table since 1884 because the soil's water content remains roughly 20% both above and below the height of the water table . </P> <P> During the first phase of construction (1848--54), the walls were built with bluestone gneiss rubble, ranging from very large irregular stones having a cross section of about 5 by 10 feet (1.5 m × 3.0 m) down to spalls (broken pieces of stone) all embedded in a large amount of mortar . The outer surface is marble stones 14 to 18 inches (36--46 cm) thick in 2 - foot (61 cm) high courses or rows horizontally encircling the monument . Although each course contains both stretchers (stones parallel to the wall) and headers (stones projecting into the wall), about two to three times as many stretchers as headers were used . Their joints were so thin that some stones pressed on bare stone below them, breaking off many pieces since it was constructed . The batter or slope of the outer surface is 0.247 inches per foot (2.06 cm / m, 1 ° 11'). The inner surface has disorderly rows of smaller roughly dressed bluestone gneiss . The base of the first phase walls has an outer dimension of 55 feet 1 ⁄ inches (16.80 m) square and a thickness of 15 feet (4.6 m). The interior well is 25 feet 1 inch (7.65 m) square and has square corners . The weight of the first phase walls up to 150 feet (45.7 m) is 22,373 long tons (25,058 short tons; 22,732 tonnes). </P> <P> During the second phase (1879--84), the walls were constructed of smoothly dressed (ashlar) large marble and granite blocks (rectangular cuboids) laid down in an orderly manner (Flemish bond) with thick joints . Two - foot high marble surface stones, using an equal number of stretchers and headers, were backed by granite blocks from the 152 - foot level (the first course above the rubble) to the 218 - foot level, where marble headers become increasingly visible on the internal surface of the walls up to the 450 - foot level, above which only marble stones are used . Between the 150 - and 160 - foot levels the inner walls rapidly slope outward, increasing the shaft well from 25 feet 1 inch square to 31 feet 5 ⁄ inches (9.59 m) square with a corresponding decrease in the thickness of the walls and their weight . The second phase walls at the 160 - foot level were 8 feet 7 ⁄ inches (2.63 m) thick, which, combined with the larger shaft well, yields an outer dimension of 48 feet 8 ⁄ inches (14.85 m) square at that level . The top of the second phase walls are 34 feet 5 ⁄ inches (10.50 m) square and 1 foot 6 inches (46 cm) thick . The second phase interior walls have rounded (2 - foot (0.61 m) radii) corners . The weight of the second phase walls (from 150 feet to 500 feet) are 21,260 long tons (23,810 short tons; 21,600 tonnes). The walls of the entire shaft (combined first and second phases) are 500 feet 5 ⁄ inches (152.530 m) high . </P> <P> The first phase of the walls was constructed under the direction of William Dougherty . Its white marble exterior came from the Texas quarry now adjacent to and east of north I - 83 near the Warren Road exit in Cockeysville, Maryland . The quarry was named for the Texas Station (no longer extant) and 19th - century town on the Northern Central Railway . During the first phase it was operated by Thomas Symington, but is now operated by Lafarge and no longer produces building stone . The second phase of construction was under the direction of Lt Col / Col Thomas Lincoln Casey of the U.S. Army Corps of Engineers, who removed two defective courses added by the Know - Nothings and the last 152 - foot course added by Dougherty before Casey began his construction . The next three courses of white marble (152--156 feet (46--48 m)) came from Sheffield, Massachusetts, while all courses above them came from the Beaver Dam quarry just west of the 19th - century town of Cockeysville . The latter quarry is located on Beaver Dam Road near its intersection with McCormick Road . During the second phase the quarry was operated by Hugh Sisson, but is now flooded, is called Beaverdam Pond, and is the home of the Beaver Dam Swimming Club . Both 19th - century towns are now within the city limits of Cockeysville . </P>

Where did the stone for the washington monument come from