PHYSICAL STRUCTURE
SALT MEASUREMENT
POPULATION STATISTICS
| PHYSICAL STRUCTURE |  |
The Salt Monument measures 9.5 feet high (2.9m) and 7.5 feet (2.3m) wide and deep.The four foot (1.2m) cube has an interior area of 64 cubic feet (1.8 cubic meters) and is made of 3/4" (2 cm) plexiglass. It was fabricated and engineered by the Denver plant of an international plastics company. Completely empty, the cube itself weights about 450 pounds (204k). The necessary thickness of the material was determined based on engineering calculations rendered by licensed structural engineers. Factors of tensile, flexural, and compressive strength given the weight and density of the salt were taken into account. The Salt Monument is engineered to hold up to 4,000 pounds (1,800k) of salt, which would represent over 14 billion people - far more than even the highest population estimates. It is expected that a slight, but structurally harmless, deflection of the cube faces may occur if it holds over 3,000 pounds (1,400k) of salt. Interestingly, the bonded edges of the cube are actually stronger than the faces.
The uppermost corner of the pivoted cube houses two tetrahedrons, which form the opening for filling and cleaning the Salt Monument, as well as for adding the daily births. (A tetrahedron is a three-dimensional figure with four triangular faces; in both of the Salt Monument tetrahedrons, three faces are solid and the fourth is open.) The apex tetrahedron (at top) swivels on a plastic dowel and is opened by magnet. The birth tetrahedron (inside) has a funneled 0.136" hole drilled into it, to allow for the slowest possible free-flowing stream of the birth salt.
At the bottom corner of the pivoted cube is the death exit, controlled by a precision, adjustable, ball valve. This opening serves for taking out the daily deaths.
The cube was completed in December, 1998. Refinements were made during January, 1999. Testing was conducted during February and the first filling of the Salt Monument was completed in March, 1999. Although the daily world births/deaths have been conducted every day beginning September 17, 1997, the Observance has occurred at the actual, completed Monument every day since March, 1999.
The base is made of 2-inch (5cm) square tubular steel, and itself weighs about 200 pounds (90k). It was welded and powder-coated by local firms in Boulder County. The upper triangle of the base, on which three faces of the cube rest in the pivoted position, supports the enormous weight of the Monument by virtue of matching the angle of the cube at 55 degrees thus distributing the tonnage. It is estimated that the base could support 10,000 pounds (4,500k) or more.
| SALT MEASUREMENT | |
Research into what type and grade of salt would be best suited for the monument began in 1997 with The Salt Institute in Washington DC and with Morton Salt at their Chicago headquarters. Numerous sizes and types of salt were tested and measured. In the end, common table salt was selected based on considerations of size, uniformity, cubic form, solubility, availability, familiarity, and cost.
The entire premise of the Salt Monument's mass of salt is based on the average weight of an individual grain of salt multiplied by billions. It should be noted that determining the average weight of a grain of salt is no less daunting than figuring the average weight of a human being from random groupings. Just as people can actually range in weight from three pounds to three hundred, so do grains of salt vary. Some grains of salt are scarcely a speck, while others appear formidable by comparison. Samples of 20, 40, 100, 200, 400, and 1200 grains of salt were weighed on several different microanalytic scales. Final weigh-ins were conducted by analytic balance specialists on a certified electrobalance scale which measures micrograms, that is, six decimal points of a gram.
Based on these findings, for the purposes of the Monument, the average weight of a single grain of salt was calculated as .1208 milligrams. From this, each 25 pound (11.3k) bag of salt is estimated to contain about 90 million grains of salt.
The Salt Monument currently holds about 1800 pounds (815k) of salt, representing the total world population of about 6,741,000,000 (January, 2009). The total weight of the Monument, including the weight of the cube and the base, is thus almost 2,500 pounds (1,134k).
| POPULATION STATISTICS | |
The salt representing the daily births and deaths was initially measured based on weight, using the .1208 milligram/grain figure. For ease of the daily process, i.e. rather than needing to use an analytic scale every day, the volume of those amounts of salt was measured and is used to approximate the daily world births and deaths. About 369,755 people are born each day, which is represented by about 1/4 cup of salt, and about 150,835 people die each day, which is represented by less than an 1/8 cup of salt (June, 2008).
It should be noted that although every effort has been made towards accuracy, the Salt Monument is a symbolic representation of population figures. It is not unreasonable to expect a plus-or-minus 10% margin of error in the actual, literal number of grains of salt contained in the Monument.
The most respected and reliable sources of world population information, the International Data Base (IDB) of the International Programs Center (IPC) at the U.S. Bureau of the Census in Washington DC and the United Nations Population Fund have been utilized for population statistics. The IPC figures are updated and revised twice a year, which the Salt Monument incorporates in its representations. Of course, such statistics on a global scale cannot be precisely exact, but are considered accurate estimates, again with the understanding of a margin of error.
