Chicago As Seen From Around South Lake Michigan

Quote from: cikljamas on May 21, 2015, 10:58:18 AM

Quote from: mikeman7918 on May 21, 2015, 10:54:07 AM

Your doing your calculations wrong.  You are calculating the height of the bulge correctly but that's not how you calculate visibility distance.  You have to find out the arc distance at which your line of sight is tangent to the sphere of the Earth for both objects in question and add them together to get the maximum distance at which those two objects can see each other given their altitude and the size of the Earth.  If you are going to pretend like you care about math then at least do a bit of research first.

Maybe you have missed this part:

A very striking illustration of the true form of the sea horizon may be observed from the high land in the neighbourhood of the head of Portsmouth Harbour. Looking across Spithead to the Isle of Wight, the base or margin of the island, where water and land come together, appears to be a straight line from east to west, a length of twenty-two statute miles. READ MORE : http://www.sacred-texts.com/earth/za/za13.htm

From a vantage point in Portsmouth Harbor the Isle of Wight is only about 12 miles across.  One would have to be in the Fawley area to even be perpendicular to the island's 22 mile length.

Yes, I looked at those images already.  Portsmouth Harbour is the small harbour to the right where it says 'Portsmouth'  Spithead is the area of water pretty much directly between that harbour and Isle of Wight.  From that direction, the shoreline that is being faced it only about 12 miles.

Quote from: 29silhouette on May 23, 2015, 09:46:07 AM

Yes, I looked at those images already.  Portsmouth Harbour is the small harbour to the right where it says 'Portsmouth'  Spithead is the area of water pretty much directly between that harbour and Isle of Wight.  From that direction, the shoreline that is being faced it only about 12 miles.

So Rowbotham was mistaken about the basic facts, not just the conclusion. Did the man do anything right?

If the island is 12 miles wide in his view, not 22 as stated, the "bow", grossly exaggerated in Fig. 20., is only about 24 feet, not 80 as claimed. In that case, it would amount to only 0.04% of the 12-mile FOV in the theodolite, not the 0.07% previously estimated using the incorrect length for the island from the observation point.

Fig. 19. is a much, much better representation of (as in "indistinguishable from") the actual view. Fig. 20. is willful misrepresentation to dupe the ignorant. cikljamas falls for stuff like this every time. What does that say?