How were effigies of Mount Rushmore carvedFour giant faces look to the horizon from the side of a granite mountain located in United States, South Dakota. If they were also sculpted bodies, each figure would measure about 140 m high.
They are the faces of four former Presidents of that country, carved on the top of Mount Rushmore with pneumatic drills and dynamite by men perched on the edges of the slope. The imposing work took 14 years to complete, and was directed by John Gutzon Borglum, (picture below) a famous American sculptor of Danish origin.
The sculpted mountain is a national monument, and the four characters, chosen to represent the ideals of the nation, are George Washington, Thomas Jefferson, Abraham Lincoln and Theodore Roosevelt.
The idea of erecting the monument emerged from the historian Doane Robinson in 1923, he proposed was esculpieran effigies of heroes like Kit Carson and Buffalo Bill in a few columns of granite called the needles located in the same area as the Mount Rushmore. But Borglum considered that neither the column nor the project were appropriate, for he had the conviction that the work should have national significance.
The sculptor John Gutzon Borglum built their models work on a scale of 1:12 (an inch on these would be tantamount to a foot on the rock). His son Lincoln Borglum measures Jefferson model to make the transfer to Mount Rushmore. Once at the top of this helps operate a machine to measure and mark the drilling points.
The monument was sculpted between 1927 and 1941 at a cost of $990 000, mostly federal funds. The sculpture itself took 6.5 years to complete, but the work was slow because of financial problems in the early years, as well as climatic factors. The majority of people who sculpted the faces were miners or beds of the region, and during those 14 years worked about 360 employees in teams of 30 people on average.
Heads planning: Borglum chose Mount Rushmore, 1,745 m in height, for the fine grain of his granite, but even so it was necessary to remove tons of stone to expose the appropriate rock; for the head of Washington is desbastaron about 9 m, and the Roosevelt about 37 m. About 450 000 tonnes of rock, which are still at the foot of the mountain were removed throughout the work.
Borglum decided to sculpt head by head, starting with the of Washington; made her a model of 1.5 m in height (1/12 of the size that would be the real), on whose top set a plate marked in degrees flat. In the center of this and about a pivot then mounted a horizontal bar of steel of 76 cm. long graduated in inches, and bar suspended a plumb also marked in inches. When you turn the bar and move the Plumb to anywhere on the face, like a nostril, necessary measurements could be made.
To transfer the measurements of the model to the mountain, settled a similar mechanism that is 12 times larger than at the top, at the point chosen for the top of the head of Washington. Borglum called indicator machine fixture, and the men responsible for measuring, indicators.
Rock styled: After choosing the points, rock drilling to depth marked by the indicator to place dynamite in the holes and to fly about 15 cm. of the rock. Drilling had to be very precise, as a too-deep cut would remove stone over and would not be possible to restore it. Each drill worked attached to a leather seat hanging from a cable attached to a winch, a hole of 39 kg. of weight pendant of the same cable. The winch operator was situated at a point from which could not see to the punch, so I placed a boy subject with a safety device at the edge of the cliff so it relayed messages between them.
Work being hung around 76 m from the top was not easy, so to make enough pressure when drilling, Drillers before should reach a stretch of chain and pass it behind the seat. then they noticed the chain with steel nails in the rock.
Heads of State of four former Presidents of the United States faces were carved in Mount Rushmore: (from left to right.) George Washington, Thomas Jefferson. Theodore Roosevelt and Abraham Lincoln.
Bits is embotaban every 15 minutes, and every day a blacksmith had to sharpen hundreds of them. As Drillers moved from one point to another of the mount, the barracks got loads in the holes; the blasts occurred two times a day: at lunchtime and at the end of the working day.
To cut and carve the stone to give the final dimensions, Drillers made close together lines of small holes to remove the final layer with steel hammers and wedges, and then smoothed"the surface with special drills.
Borglum decided to sculpt head by head, starting with the of Washington; made her a model of 1.5 m in height (1/12 of the size that would be the real), on whose top set a plate marked in degrees flat.
Setbacks: The head of Washington was completed in 1930, and soon began working with the Jefferson. He started on the left of the first (from the viewer's perspective), but in 1934 appeared a stratum of rock of low quality that forced to destroy the incomplete head and relocate the sculpture to the right of Washington.
As the rock on the other side had large cracks, it was roughing 18 m to achieve the appropriate layer, leaving only the thick enough between the cliff and the deep canyon situated behind it. But a split in the place where would go nose forced Børglum to alter the angle of the head, and other minor cracks were filled with a mixture of linseed oil, white lead and pulverized granite.
The head of Jefferson also has the only patch that is needed in all the work: to sculpt the upper lip appeared a reef of feldspar which could not be styled, so was eliminated and left a hole of about 60 cm long and 25 cm. deep. At the base of the cavity two steel nails were placed to support a cap of granite set with molten sulfur.
The master touch: Each head measuring 18 m in height and, on average, the nose of each measuring 6 m in length, mouth 5.5 m wide and eyes 3.4 m from one end to the other. To give character and expression to the faces on that scale was necessary to a master touch: Borglum gave eyes a glimmer of life leaving a column of granite about 56 cm. long as a pupil, the sunlight highlights against the shadow this way.
Borglum died on March 6, 1941, at the age of 73, shortly before the monument was completed. The finishing touches were supervised by his son Lincoln, (left image) that just being a teenager had worked as an indicator to the beginning of the project.
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