Prior to 1813, essentially all of Delaware NJ was owned by 2 brothers, Nicholas and Cornelius Albertson. Nicholas owned the plateau east of town. Cornelius owned the flat land from there to the Delaware River, having inherited it from the previous owner Edward Robeson. Robeson's daughter Mary was Cornelius' wife.
Mary Robeson Albertson died on May 27, 1807. Her estate was left unsettled until after Cornelius' death, almost 6 years later on March 21, 1813. The settlement was finally reached in 1815. The hand-drawn map below (hat tip to the "Knowlton and Blairstown Twps, NJ" Facebook group) shows their 235 acres split among their children. I've placed it side by side with the sketch I made from Nicholas' 1816 deed selling a parcel of his land to his son Henry. According to that deed, the NW corner of Henry's purchase is a corner of Cornelius' estate, and Henry's western boundary is a line of Cornelius' estate. So regardless of how your browser renders it, these two properties are adjacent and the top line of Henry's purchase is a continuation of the top line of Mary's estate.
For anyone wondering about the uneven split on the left, the lines were not drawn by Mary or Cornelius, they were negotiated by the heirs. Elam, David, Sarah (Mrs. Jacob Shoemaker) and Abigail (Mrs. Joseph Cammel) had all moved to Pennsylvania with their families by the time the settlement was reached. They were given joint title to the largest parcel at the north end with the obvious intent of selling it and splitting the proceeds. This was the most developed part of the property, containing the main house and a working mill. Between these improvements and the extra land, the heirs calculated the value of this slice to be 4 times that of the other three slices.
Uriah and Edward both pre-deceased Cornelius. Uriah died in 1799, well before either of his parents. As part of the same settlement, his parcel was split among his 5 children as shown here. It's a preposterous division, designed only to be recombined and sold. There are 8 equal shares. The two daughters got a share each, the three sons 2 each but none contiguous, assuring the uselessness of all 8 individual plots - those strips are barely 75' wide! Edward's heirs were all minors, and made no side agreement, taking joint ownership of their father's share. Later in 1815 John joined his brothers in Pennsylvania, selling his parcel to the noted surgeon Dr. Jabez Gwinnup of Belvidere, who in 1798 had amputated the diseased right leg of Nicholas Albertson, extending his life by 20 years. Gwinnup built a house that still stands along Delaware Rd.
Though Edward's widow Sarah survived him by many years, their children Cornelius, Hugh and Susanah were placed under the joint guardianship of Edward's cousin Henry (the same Henry, son of Nicholas), and Sarah's brother John Ferguson, who lived a couple of miles to the north. Henry's wife Mary was a Ferguson too, sister of Sarah and John, which might help explain the odd custody arrangement. I think another explanation is closer to the mark, though - Henry wanted the profits from operating the farmland Edward inherited for as long as he could get them, and he used his kinship with Edward and his wife's with Edward's widow to that end. Of course having a teenage niece around the house to help Mary with their growing young family was a definite plus.
Step 3. No, really, put it down on a map
The map below is built on an aerial view of Delaware NJ, from a fly-over mapping of New Jersey conducted in 1956, using the Gimp image editor to overlay lines and text. I purchased the base image from Historic Aerials, curators of a large collection of historical aerial surveys. The scale is almost exactly 10' per pixel - the scale below the map, screen-grabbed from their web site, is 72 pixels wide, so 72 pixels = 725'. You can run your mouse onto the map to see the original image without the overlay.
My intent was to replicate the Mary Albertson estate map and the sketch of Nicholas' deed to Henry on the 1956 aerial photograph, guided by whatever physical evidence the photograph would provide. I started out by drawing the lines that were visually the most obvious - the nearly horizontal line across the top, the nearly vertical line up the middle, and the other 2 lines bounding Areas I and II which together constituted Nicholas Albertson's 170 acre plantation. Next came the boundaries for Area V, which was Eagle's Nest Camp at the time of the photo and whose lines are also easily visible. There are a few faint features on the ground guiding the line at the bottom of Area VI. For the other two I simply continued lines visible on adjacent properties.
The results are striking, down to the way the property lines meet the bends in the river. It's safe to say, beyond a reasonable doubt, that the property Eagle's Nest Camp and Holiday House were built on is the slice of Edward Robeson's land inherited through his daughter Mary by her grandchildren Susanah, Cornelius, and Hugh. With some math (warning: math ahead) and a decent calculator, it's possible to calculate the lengths and angles of the lines on this map and convert them to the form used in deeds, allowing us to double-check these lines and the deed and estate map against each other.