2018-08-17 / Columnists

A Look at History

Surveyors’ Point Stands on Southwest Corner of Marquette Park

Surveyors’ Point

Every year, hundreds of thousands of people walk or ride through or past the street corner where Main Street and Fort Street come together. It is one of the most picturesque spots on our world-famous Island. Down Main Street to the southwest, point-of-sale machines total up numbers in the century-old buildings that line the pavement. To the south and east are the colors of yachts and the blue of Lake Huron. To the north, spread out above green Marquette Park, are the whitewashed walls of Fort Mackinac. Turning through this street corner continuously, for up to nine hours every summer day, are the yellow and red horse-drawn passenger wagons of Mackinac Island Carriage Tours.

In this riot of color is a spot of polished bronze. At almost the corner of the street, right next to the concrete separation that marks off Marquette Park from the pavement, rises from the ground a steel pipe with an engraved copper cap. The letters scratched into the plate are worn and tired. The letters read: “Elevation 596.5 ft.”

Probably the most overlooked landmark in Marquette Park is this corner survey post at Fort and Main streets. It is more noticeable now that the large tree that shared this corner was removed last winter. Probably the most overlooked landmark in Marquette Park is this corner survey post at Fort and Main streets. It is more noticeable now that the large tree that shared this corner was removed last winter. Survey markers are the foundation stones of public and private land use in the United States. The founders of Roman land law, in the centuries before the time of Jesus Christ, were among the first humans to realize that it was possible to build an entire legal system and economic structure of thought upon the idea of sited lines that exactly separated “your land” from “my land.” Their engineers trained by land law from childhood to ask the question “where am I?” and answer it in relatively precise ways, then used this knowledge to perfect military technologies. They turned ideas largely invented by others, such as the Greeks and the Carthaginians, into the fabled Roman tools of war. Fearsome weapons were dragged out onto battlefields. Tended by engineers who knew exactly where they were and how high up what they launched would fly, their projectiles killed and terrified men from a countless list of Rome’s enemies and helped Rome conquer the known world. The powderless Roman cannon, the “ballista,” could throw a cannonball-sized weight so far and so accurately that to this day the science of throwing things is called “ballistics.”

At left: Marred by the abuse of the ages, the copper cap on this survey marker record the elevation of 596.5 feet. At left: Marred by the abuse of the ages, the copper cap on this survey marker record the elevation of 596.5 feet. Ever since the time of Rome, there have been close ties between the sciences of surveying land, gauging elevations, and siting ballistics weaponry. A young mathematics whiz with the strange (to the French) name of “Napoleon Buonaparte” showed up at the France Royal Military School one day in 1784 to study artillery. He graduated a year later and, after teaching a close circle of friends how to rapidly survey a battlefield and put down “field pieces,” he and his marshals conquered almost all of Europe – including some patches of the continent that not even the Roman Empire had been able to reach. The U.S. Military Academy, West Point, was founded by Thomas Jefferson in 1802 as Napoleon’s career was reaching its height. Naturally, the new service academy placed surveying and three-dimensional mapping at the center of its curriculum. It was a lesson that the young American armed forces badly needed to learn. In 1814, as West Point was finishing up its 12th year of operation, a U.S. freshwater fleet appeared in the Round Island Channel just off Marquette Park and tried to fire its heavy guns up at British-occupied Fort Mackinac. The cannon shots created futile puffs of shattered rock and gravel as they hit the bluff underneath the fort. The American cannoneers were stymied by the Fort’s elevation and could not hit their target.

Gravity is hard, but elevation, for those who know mathematics, is easy. In the days when copper markers like these were set up, it was a matter of triangles. Until the date that the first geodetic satellites were launched into outer space, a point in time that in terms of overall history was practically the day before yesterday, every spot in the United States that had a known height was connected by an endless series of three-dimensional surveyor’s triangles to every other. All of these markers, furthermore, were tied to the eternal zero line of world sea level.

American surveying crews, tramping over and around Mackinac Island and adjacent patches of Northern Michigan mainland in the years after the War of 1812, drew these triangles. They began to lay down a series of markers, permanently fixed in strategic points along U.S. shorelines and at crossroads, that paid close attention not only to space but also to height and elevation. The survey crews included officers in the U.S. Army Corps of Engineers, which was integrated with the rest of the U.S. armed forces in those days. At least two of the highest-ranking field commanders who would lead both sides in the approaching Civil War, Robert E. Lee and George Meade, were both trained in three-dimensional survey work. Meade would use this skill to effect when his men occupied the high ground at the Battle of Gettysburg.

After the Civil War, the federal government continued and perfected these surveys. The spike and cap at Marquette Park, and the benchmark numbers engraved into its worn surface, are part of what currently is officially called the National Spatial Reference System, a program operated by the U.S. National Geodetic Survey. “Geodetic” means “very precise land surveying done in three dimensions.” The steel pipe that supports our benchmark is fixed in the earth and braced against a mass of concrete so that it won’t move around any time soon. The pipe and plate mark not only the corner of Main Street and Fort Street, but also the corners of a series of surveyors’ triangles in American land, sea, and space: triangles that have been drawn and redrawn since shortly after 1802.

It must be admitted that just as this marker has been worn down by time, the usefulness of the number that it conveys on its scratched surface has dwindled down. The benchmark is 596.5 feet above sea level, but its value as a conveyor of information is in deep salt water. Handheld devices, connected by radio-controlled triangulation to new benchmarks high in the sky, can tell us where we are much more accurately than any old piece of metal. Quietly our marker sits, surrounded by the crowds of summer. Mackinac Island, already the home of many other old ways of doing things, is now the home of one more.

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