Harlshorne.] '^■'■^ [April 21, 



Prof. Chase exhibited diagrams representing certain 

 mathematical and astronomical relationships of length, orbital 

 movement and planetary distance, which he stated and de- 

 scribed, including in his subject matter of discussion the 

 possible influence of the meteor-belts. 



Pending nominations Nos. 792, 793, and new nominations 

 Nos. 794 to 802 were read. 



On motion, the Committee appointed at a previous meet- 

 ing to consider the expediency of an exhibition of the Pro- 

 gress of Science in the last hundred years, was discharged 

 from further consideration of the subject. 



A request by letter from Mr. Etting that the Society per- 

 mit the exhibition of its original drafc of the Declaration of 

 Independence by the city in the Museum of the City 

 Hall, was, on motion, referred to the Curators to report. 



And the meeting was adjourned. 



ON SOME DISPUTED POINTS IN PHYSIOLOGICAL OPTICS. 

 By Henry Hartshorne. 



{Read before the American Philosophical Society, April 21, 1870.) 



I. On the Theory of Erect Vision, with Inverted Retinal 



Images. 



As it has been ascertained, by both mathematical and pliysical demon- 

 stration, that the image of every object seen must be inverted upon each 

 retina, several explanations have been offered for tlie correspondence of 

 our sight with the actual position of visible things. The most prominent 

 views advanced are the following : — 1. That we do see everything inverted, 

 but that the correction has been obtained, and has become habitual and 

 momentary, through experience; 2, tliat tlie reversal of all images is eirccted 

 by tlie crossing of the filaments of the optic nerves; so that, e. g., all the fila- 

 ments from the upper part of the retina go to the lower part of the optic gan- 

 glia at tlie base of the brain, and rice-rerm; 3, that we do not mentally regard 

 the image or picture upon the retina at all, but look from the retina, at the 

 object; or, as one authority upon the sul)ject prefers to express it, "the 

 local cliange excited in the retina must lie conveyed to the optic nerve, 

 communicated to the brain, and again, in an inverted direction, projected 

 outward; througli this double inversion the i)rojected image corresponds to 



