Ok, Now having dealt with “experiment” 10, we will look at “experiment” 11, and i will do this in a few bites as it is a relatively long chapter.
At the start he uses the East pier at Sussex, as well as a balloon to try to show the dip of the horizon does not exist.
The pier observation has the height of the observer at 34 feet from the water, and he says he uses a “large wooden quadrant” which is essentially a plumb bob with a wooden protractor.
https://en.m.wikipedia.org/wiki/Quadrant_(instrument)
He claims that he could not measure the dip of the horizon therefore it does not exist.
The calculation and tables for a height of eye of 34 feet gives a dip of the horizon of 5.7 arc minutes, or less than 1/12 of a degree. This would have been pretty much impossible to see with the naked eye, and as well as the problems of making the plumb bob steady in any breeze, renders the above observation pretty much useless.
The second “observation” relates to an observation from a balloon, and he claims that such a dip
“
would be so great that the aëronaut could not fail to observe it; instead of which he always sees it "on a level with his eye," "rising as he rises," and "at the highest elevation, seeming to close with the sky."This is dealt with in the discussion of “experiment” 10, And will result in a dip of the horizon of 1 degree and 40 minutes, which might have been possible to measure with a quadrant, but of course he is relying purely on an account taken third hand from a publication some years previously, so it cannot be verified.
He also goes on to list a few places that he has visited and claims to have taken his plumb bob and wooden set square to and says he did not observe any dip, such as;
1, Arthurs seat (elevation 251M ) dip would be 28arc minutes, (also pretty windy, and a very small arc of the horizon to view),
2, Hills near Brighton racecourse, (no sure as to height as he did name them), but have taken the highest hill nearby at 120M elevation, Dip of 20 arc minutes.
3, Some hills on the Isle of Wight, (Again none named), but i have taken some of the highest and rounded up to 250M, Dip of 28 arc minutes,
4, Steep Holm, Elevation 78M, Dip 15.7 arc minutes.
5, Hills near Plymouth, 125M (Rame head) Dip 20 arc minutes
6, Irelands Eye, Elevation 32M Dip 10 arc minutes,
Above is a list of some of the places he visited, and claimed to have taken readings with his plumb bob and quadrant, and all of them suffer the same issue, they are ALL exposed locations, and the UK is not known for its still and calm airs! And as can be seen, low elevations, with low dip arcs, and as the equipment used is pretty imprecise, it is easy to see that he could probably not have made any meaningful observations of those dip angles.
He was also (i would suggest) suffering from confirmation bias, he was looking for zero dip, therefore he found none using an imperfect device.
More to follow;