The vertical-horizontal illusion; an experimental study of meridional disparities in the visual field (1917)
Ritter, Sarah Margaret · Princeton, N.J. and Lancaster, Pa., Psychological review company · leaf 58
ce, 85 mm. and 30 mm. were chosen for the shorter standard lengths, and discs 3 and 2 were made to correspond respectively with these. Thus the two outer borders become 55 mm. each, while the re¬ maining two are determined by the radius of the smallest disc (7.5 mm.) and the difference between that… … Now the value of S. i is nowhere directly determined, since a standard of so short a length was impracticable. It is obtained.
Optical illusions
Internet Archive · Princeton Theological Seminary Library · Public domain (published before 1931). Free to use for anything.
![An illustration from Nicolai Copernici Torinensis De reuolutionibus orbium coelestium, libri VI : Habes in hoc opere iam recens nato, & aedito, studiose lector, motus stellarum, tam fixarum, quàm erraticarum, cum ex ueteribus, tum etiam ex recentibus obseruationibus restitutos: & nouis insuper ac admirabilibus hypothesibus ornatos. Habes etiam tabulas expeditissimas, ex quibus eosdem ad quoduis tempus quàm facillime caculare poteris. Igitur eme, lege, fruere. [Line in Greek] (1543)](https://img.insideoutlibrary.com/img/200/ia-nicolaicopernici00cope-265-170.webp)
