Notice of a "peculiarity in Vision. 265 



fail. In my course of study in natural philosophy at col- 

 lege, I was particularly attentive to optics, yet I discov- 

 ered no clue to the difficulties under which my vision 

 labored. Having clearly ascertained that I was in some 

 sense short sighted, I hoped to find a remedy in the use of 

 common concave spectacles, but after repeated examina- 

 tions of various assortments of glasses, I became much dis- 

 couraged. Two years since, however, while in the city of 

 New York, I purchased a pair of concave glasses, of No. 5, 

 not because they suited me, but because I wished to try 

 their influence on my sight. My first attempt at using them 

 was in viewing some shipping in the harbor, when I was 

 greatly surprised to find that all the horizontal portions of 

 their rigging were seen with much greater, and the vertical 

 portions with much less precision than when viewed with the 

 naked eye. This new and curious fact suggested the pro- 

 priety of pretty extended experiments on my sight, both with 

 and without glasses. And first, with the naked eye — I then 

 found that way vertical line as 1 — 2, (see the diagram below,) 

 was seen with much much greater precision than any hori- 



1 zontal one 3 — 4, and that to see 3 — 4 with the same 

 precision with which I had seen 1 — 2, it was neces- 



j sary to turn my head aside a full right angle,* and 



2 that too, at the expense of losing the clear view of 

 1 — 2, and I also found that in viewing the circumference of 



any circle, as C j the portions that approach nearest to a 



vertical line, as 1 — 3 and 2 — 4, were seen with more precis- 

 ion and at a greater distance than the portions 1—2 and 

 3 — 4 which approach nearest to a horizontal line. 



In strict accordance with the principles thus far developed, 

 I found, that squares were seen in the form of parallello- 

 grams, circles in the form of ellipses, and spheres in the form 

 of spheroids. I found too, that in viewing the human coun- 

 tenance, the eyes, mouth and chin, were seen less distinctly 

 than the nose. 



In the next place I tried the same experiments in the use of 

 my glasses, and found an exact and reciprocal change of each 

 of the above mentioned laws of my vision, that is, horizontal 



* With the head turned aside at an angle of 45°, the lines 1 — 2 and 3 — 4 

 were seen with equal plainness, and in a degree intermediate between the up- 

 light view of the two lines. 



Vol. XIV.— No. 2. 8 



