104) “The constellation Vulpecula can be seen from 90 degrees North latitude, all the way to 55 degrees South latitude. Taurus, Pisces and Leo can be seen from 90 degrees North all the way to 65 degrees South. An observer on a ball-Earth, regardless of any tilt or inclination, should not logically be able to see this far.”

Incomprehension of the model

Again, as in #103, Mr. Dubay failed to include the earth's rotation and the constellations span of arc into his "logic".
Vulpecula has a declination roughly between +20° and +30°. With its lowest declination of +20° it can be seen anywhere north of °70N all the time. Subtracting 90° to the south will give you the southermost place, where it will rotate into view at some time. At 60°S it can be still entirely visible, at 70°S it's completely gone. These are the roughly 65°S that Mr. Dubay claims to be impossible..

Same goes for Taurus (between -1° and +30°), Pisces (-6° to + 34°) and Leo (-7° to +33°). Wikipedia puts their "average" declination between +15 and +19, which I think is an unnecessary abbreviation, as it doesn't display the 40°-arc that Pisces and Leo describe (declination-wise).

65°S is therefore not an exact value for these three. For possible complete visibility (at times) it's rather 60°S for Taurus (up to 89°N), 56°S for Pisces (to 84°N) and 57°S (to 83°N) for Leo. However, since most of their brightest and defining stars lie roughly in the middle between their min- and max declinations (broadening the field by 5 to 10°), 65°S and 90°N is still an OK rule-of-thumb value.

http://200proofsearthisnotflat.blogspot.co.uk/2016/02/debunking-dubay-100-109200.html

Spheres are a hard shape to see.

Really? This constellation is at declination +25. `Logically' I'd say it is visible from 25+90=115, or the entire hemisphere, down to 25−90=65, or most of the inhabited southern hemisphere. (With a really rough estimate).

Do you want a picture, or what?

A really bad sketch of the situation. Note the green and blue sight fields.

So no, that actually makes perfect sense. Now try explaining that by your flat-earth model, in particular the specific 

http://blog.daimonie.com/2015_11_01_archive.html