St. Leonard's Creek on the Patuxent, the Chesapeake's sixth largest river, was formed by the slow inundation of a forested valley as sea levels rose and land subsided during and after the melt of great continental glaciers. The process, which commenced 12,000–14,000 years ago when the coast was far to the east, filled St. Leonard's nooks and crannies and formed Osborn Cove.

The several hundred acres of land adjacent to Osborn Cove, called "Smuggs Folly," were patented to Henry Osborn in 1669 from the Elton Head estates of Lord Baltimore under authority of the English King Charles II. It first appeared on a nautical chart of the river produced by Alexander Bache's Coast Survey crews in the 1840s.

Surveyor R. D. Cutts included the tiny embayment in his mapping probably more by chance than design. In the map, the cove had a curved sandbar stretching out from its northwest-facing shoreline. Spits like this were hardly unique; they appeared at the mouths of seven nearby coves. They were (and are) formed and sustained by the supply of sand eroding from roughly 30-foot high banks of sand, gravel and clay sediments.

What is remarkable is that even without human intervention, these sand spits have persisted and were stable over time.

The chart suggests the land surrounding Osborn Cove had been cleared for agriculture, but in some places, small copses had been spared the axe.

No dwellings were recorded in its 118-acre watershed. During the next century, American chestnuts reforested parts of this landscape.

The U.S. Coast Survey returned to the Patuxent River estuary at least once during the mid-19th century, but no more shoreline was mapped on St. Leonard Creek until a more extensive survey was undertaken in 1907–8.

The story of this survey sheds light on the work and also upon the dedicated people who did it in a time before electronic calculators, computers and lasers.

H. A. Seran had just graduated from what he called a "freshwater college" in Ohio when he was hired by the U.S. Coast Survey and was sworn in July 1, 1907, as an assistant for field and office work. Later in July, he and eight other assistants received orders of transfer from the Computing Division in Washington, D.C. to join the survey schooner Matchless on Pocomoke Sound. An article in which he reminisced about this experience was published in 1930 in the Bulletin of the Association of Field Engineers and is the source of many of the anecdotes in the column.

They boarded a Bay steamer at Baltimore and sailed for Saxis, VA, across from Maryland's Eastern Shore.

Seran was totally green. While in Washington, D.C., he had struggled unsuccessfully with the mathematics of Wright and Hayford's "Methods of Least Squares" — laborious arithmetical methods that melded together a "best fit map" from many slightly differing observations.

Like many young surveyors just starting out during that time, Seran had no idea how to handle these complex tasks, unlike some of the old codgers in the Coast Survey's D.C. offices, who had developed some of the equations. (These calculations are instantaneous on a computer today.)

With them on the steamer trip to Saxis was Capt. O. W. Ferguson, who was to relieve then-serving Captain Vinal. The latter had one of the ship's boats waiting for their arrival and the young men joined Matchless anchored about a quarter mile offshore.

To Seran, who'd never seen such a vessel firsthand, it appeared like a 100-foot long yacht.

He would soon have a more mundane view. Below decks on this ship, built before the Civil War and then almost half a century old, he would become familiar with what he called "the dark bilges and forecastle, the stuffy and smelly wardroom and cabin, the inadequate toilet facilities and other antiquated features."

That hot summer night, his first aboard, he left the porthole over his bunk open. The ship was swinging between wind and tide, when a stiff breeze sent a wave sloshing along Matchless' side. Several gallons of Pocomoke Sound water cascaded into his bunk. He spent the rest of the night crammed in one berth with a fellow surveyor, Mr. Purton.

They appeared on deck next morning fitted with smart New-York tailored Survey uniforms, which had just arrived aboard the ship. Matchless' forecastle crew sneered at these uniformed incompetents, but, Seran remembered that they felt "the close-fitting blouse with its tight collar was a neat appearing rig and Purton and I would not have exchanged places with the President of the United States that day."

While off duty, the young men had the chance to go far up the Pocomoke River's deep, cypress-lined channel to Pocomoke City. They also visited Crisfield, which was the then-acknowledged seafood capital of the Eastern Shore and "a city built largely on oyster shells." The offal from fish cleaning and oyster shucking was abundant, and Seran recalled that,

"the buzzards were so thick overhead that a random shot in the air most likely would have brought one tumbling down."

The year was 1907 and the Jamestown Exposition was commemorating North America's first permanent English settlement 300 years earlier. Seran took off a few days and traveled to see the show. He recounted that he "stayed at the Inside Inn, and well remembered the quarter mile or so of mudflats that stretched Bayward in front of the Hotel at low tide."

They were off Saxis four months completing the survey of Pocomoke Sound, and by that time, the whole crew had begun to work efficiently as a team.

Their next set of orders sent them across the Bay to Solomons Island. Sailing at night against northerly winds, they tacked slowly toward their destination. They anchored in the bight between Little Cove Point and Cedar Point at the river's mouth until morning.

They were using Bache and Cutts' chart from 1848, then almost 60 years old. Part of their chore was to remedy any problems it had.

Seran was still asleep in his bunk when the ship ghosted in toward the harbor, skirting the north edge of Middle Ground, a shoal off the island's face. The leadsman sounding the depth stood just above Seran's bunk porthole and called out "3 feet!" His call brought the young man out of his bunk in a second. But the helm and captain knew what they were about and there was no problem.

Once in the harbor at Solomons, with Moll's Leg shoal ahead and Ship Point to starboard, Ferguson went ashore in one of the boats and negotiated a place at one of the piers.

Seran noted that they "settled down to a life of Reilley for some time." And, of course a lot of serious work, as the year slid into autumn and toward the new year of 1908.

Because his name would be on the published charts, Ferguson demanded that the work be accurate. He was a stickler in training his crews, and was considered by his superiors "the best precise (plane table) leveler in the United States."

At first, the young surveyors looked with trepidation at the plane table outfits they'd been issued, but eventually mastered the techniques and were soon "humming along" on a survey of the lower Patuxent.

They progressed from the point where the mate checked every sextant angle they shot to working as independent survey crews. Two of these crews would set off from the ship's side in longboats each morning, along with a third boat for the hydrographic party that measured water depths and recorded obstructions.

From reconnaissance notes they made sketches of the overall view locating the stations (fixed points) from which triangulation (angular measures by compass and sextant) and traverse (distance) observations were made. The actual measurements made — and fit with the horrendous least squares method — controlled the final "picture" one saw on the finished chart rolled out on a navigator's table.

The survey of St. Leonard's Creek proceeded to the headwaters and paid close attention to the topography ashore.

Along the easterly bank they resurveyed Osborn Cove, adding more precise topography that showed the small valley drainages and indicated the forest now standing atop the highest rise. By 1907, the woodland was dominated by American chestnut. African American children gathered the nuts each autumn for 5 cents a pail. The sweet, roasted nuts were later sold on the streets of Baltimore and the District of Columbia at considerable markup.

The trees themselves, Ferguson later said, were timbered mostly for railroad ties.

Seran noted there was a small house with a little octagonal Victorian tower on the west side facing the creek and sitting amidst the clear agricultural land atop an eroding cliff. The house was unfinished, the surveyors learned. The husband had drowned in the cove seven months earlier, and the widow lived there alone.

A few small cedar trees had been planted around the house, which would someday shade it, as would a healthy young red oak to the southwest.

The party properly characterized the persistent sand spitalong with the small embayed tide pond it enclosed.

Ferguson's narrative report, number 2861, accompanied the finished map on the survey sheet and was received by the Coast Survey on Sept. 8, 1908. In it, he wrote, "The Patuxent is a beautiful river, the configuration of its shores and wide creeks furnish many pretty places, the heights along the shore ranging from five to 45 feet." The price of interior land he noted was about $2 an acre, and the land "was dearer (more costly) for favorite sites on the river."

Small estuarine embayments and wooded shorelines aside, the surveyor's work was vital to the economy of the Chesapeake and critical in saving human lives when a ship scudded in for cover during the Bay's fierce storms and crushing winter ice.

It seems that Seran took seriously the importance of his work and he became increasingly valuable to the Survey. Within a few years he was commanding one of the its schooners. By 1930, he was lieutenant commander of the Survey's successor agency, the U.S. Coast and Geodetic Survey.

Next month: Osborn Cove in later years.