I’ve been attempting to plot the Roper Survey upon aerial photographs of the island but I’ve consistently met with two major problems, the first of which is how to get the image aligned to true north. I've coastal charts to assist in this, Google Earth to consult and have been helped by Tank, Petter and n4n. It seems reasonable, therefore, that I should be aligning the images to less than 1 degree of error.
This is where the second problem arises. The Dunfield crater at the site of the Cave-In Pit insists upon being in the wrong place! This might mean that my copy /extract of the Roper Survey is incorrect or I’m doing something wrong. So, I consulted the main books on the mystery to find that my understanding of the Roper Survey is correct according to Rupert Furneaux but not according to Reginald Harris and D’Arcy.
I note that Furneaux spoke to Gilbert Hedden in 1971 concerning the Roper Survey and he observed that Roper had only surveyed the directions - not the Money Pit and Cave-In Shaft which were added later (Furneaux, 1972, p.119) - except that Roper was misinformed about the sites of both and so subsequent versions had to be corrected.
There are four main points of conflict. First, the Money Pit was reported to lie on the line between the Westerly Drilled Rock and the Welling Triangle but that’s not where it’s placed on the Survey. I note that D’Arcy (1978, p.120) follows the Survey and puts the Hedden Shaft on this line with the Money Pit to the west (amended in The Big Dig, p.97 and Secret Treasure, p.100). However, I feel it’s more likely that the Hedden Shaft is partly over the Money Pit rather than where Roper put it, to the west, which is also where Harris locates it (1967, p.200). Oddly, this conflicts with where Harris shows it in his diagram (1958, p.59 and 1967, p.30) which, I assume, is likely to be correct.
Second, Harris presents two conflicting accounts of the location of the Cave-In Pit. In the text it’s at the point seven rods west of the East Rock (1958, p.157: 1967, p.143), which is not where it’s placed on the Survey. Harris’s diagram also seems not to match the Survey - he appears to place the Cave-In Pit at least 10 feet to the east (1967, p.81). However, Furneaux reports a similar frustration because Hedden told him that Roper (and Harris) had got it wrong and that the Cave-In Pit lay some 20 feet south of the point measured seven rods west of the East Rock.
Third, D’Arcy reports that the Money Pit (Hedden Shaft) was 300 feet from the apex of the Triangle (1978, p.121) but this is more like 280 feet on the Survey. Harris says the distance was 210 feet which cannot, surely, be anywhere near correct. Furneaux’s diagram (1972, p.98) seems closest to the Survey, D’Arcy’s (1978, p.120) is slightly adrift but those in the Big Dig (1988, p.97) and Secret Treasure (2004, p.100) are best ignored!
Fourth, if we take a compromise that the Money Pit was about 290 feet due north of the apex of the Triangle and, by calculation, that the Cave-In Pit was about 320 feet at 14 degrees north of east (thus placing it close to the line of the assumed Flood Tunnel) then Robert Dunfield’s crater is way out of place. It cannot be centred on the Cave-In Pit which, by my reckoning, would be on its northwest rim.
D’Arcy writes, “a line drawn from the center of the Cave-In Pit to the point where the triangle’s medial line meets its base is exactly 30 rods to the southwest” (1978, p.125). I don’t want to get picky about definitions of ‘medial’, ‘exactly’ and ‘southwest’, or the fact that nobody knows for sure where the Cave-In Pit was originally, because I think I know what he means. However, someone taking this literally might suppose that the Cave-In Pit lay 30 rods northeast of a point some 300 feet south of the Money Pit (the Hedden Shaft) - which is where I believe the centre of the Dunfield crater may be - and this would be altogether wrong by about 50 feet (and I doubt the Cave-In Shaft would have been obvious 30 years after the Roper Survey).
I don’t imagine it’s important to anyone else to have this resolved but it’s important to me because the Cave-In Pit, as reported by Hedden, would seem to be at one of my rhombus points. I feel, maybe, I have the Roper Survey figured out and that the Money Pit and Cave-In Pit are positioned slightly wrongly upon it - preferring to go by what Hedden told Furneaux. This being the case, I’m unable to reconcile the location of Dunfield’s excavation east of the Hedden Shaft with the location of his excavation to the south of it (on the South Shore).
Can anyone confirm that the Dunfield crater is definitely centred upon the Cave-In Pit, as reports state? Is there any way of confirming my suspicion that maybe it wasn’t?

The diagram shows part of my reconstruction, as it relates to the Roper Survey, and the problem I have. The large dashed circle is the Dunfield excavation - I think!. So, even if the Cave-In Shaft was where Harris puts it on his diagram Dunfield would probably have missed it completely.
The significance of this for me is as follows: Points A, C, D, E and F are Map Points located on the Rhombus Rectangle (A, C and E are from the instructions on the Wilkins’ maps, D and F are from those on Palmer’s). Points B and G complement these five but G would seem to be on the site of the Cave-In Pit, as reported by Gilbert Hedden (the centre is 21 feet from the 7 rod point). My question would then be: why would somebody have been digging at a point identified by one of these seven so-called bogus maps?
So, does the Dunfield crater truly obliterate the three different points at which Hedden, Harris and Roper reported the Cave-In Pit to lie?