Rowbotham makes several criticisms such that the center of the far target was not lined up with the center of the viewing apparatus:
http://www.sacred-texts.com/earth/za/za45.htm
Why, also, was the centre of the object glass fixed 2¼ inches higher than the centre of the object of observation at the other end?
Things are not perfectly aligned here. It is a bad experiment. You can read the particulars in the link. There are also actually two attempts of viewing the experiment Wallace set up, not one. We are mixing some things here. Rowbotham chronicles the experiments in the above link. The goal of the first experiment was to get everything into a line, but results first actually showed that the middle marker was above the center line of sight of the allegedly level viewing apparatus for some reason, and the second attempt showed that it was below the center level of the viewing apparatus.
This suggests to me that this is all together a bad experiment.
Yet Rowbotham tries to argue that refraction would account for the result, and an awful lot of the chapter complaining about why his original experiment was not conducted, but fails to enlighten as to the reason why.
I see you still didnt answer my previous question regarding the
bishop jellybean method of perspective.
He claims one fact, that the telescope was 2 1/4 inches above the Center of the signal, and the marker on the bridge. He admits that the Center of the marker is at the same height as the marker on the bridge.
He seems to suggest that the Center of the marker on the far bridge should have been levelled with the top of the 12 inch disc, and the top of the bridge.
He fails to note that the BOTTOM of the marker, is still way above the marker seen on the fast bridge, even though the bottom of the marker will be 8 1/4 inches BELOW the centerline of the telescope. He does not complain about that being magnified does he?
The size of the far marker on the bridge is not described, however if the drawings are true, then it is a similar size or larger than the disc, and one has to assume it is the Center being referred to as the Center of the disc is what is at the 13 feet 4 inches, and the drawing indicated it so.
One could redraw the diagram and show the following, A at a Center height of 13’4” B at Center height of 13’ 61/4 inches, and C hieght of the bottom of 12’ 10”, but he does not.
The Center line of the disc and the far marker are in alignment at 13’4” and no amount of spinning and word play can get around that. If the world (and the canal) were flat, according to the
bishop jellybean observation then the the Center of the far bridge target A, would be above the Center of the disc, C. As tom argues the alignment is not perfect, and concedes that the Center of the telescope is above the 13’4 inches of the other 2 marks.
Remove the hoizon mark from the telescope, and try to bring the Center of the disc into transit with the Center of the bridge mark requires the telescope to be raised. The maths of this can be shown, but we know that is not a strong point of some, so probably better to skip that calculation.
Trying to use the magnification of the telescope is futile, as the telescope makes the image larger, and all by the same factor. It does not change the position of the objects.
If the telescope had a hundred fold magnification the result would have been the same, with the RELATIVE positions unchanged.
Transits or leading lines are used in navigation all the time, although we use them in the horizontal plane, and not vertical as is done here, so i am confident in what is am saying, and the use of the naked eye, or binoculars makes not a jot of difference to the position of the observer, (which is what we use them for, ie indicating if the observer is left or right of an intended course.) ie if the marks are seen one to the left or right of the other, looking at them through binoculars does not make them change relative positions.
We use them at the same as well as much greater distances than the above observations.