Erect vision from an inverted image / by B.F. Joslin.

  • Joslin, Benjamin F. (Benjamin Franklin), 1796-1861.
Date:
[1845]
Catalogue details

Licence: Public Domain Mark

Credit: Erect vision from an inverted image / by B.F. Joslin. Source: Wellcome Collection.

Provider: This material has been provided by The Royal College of Surgeons of England. The original may be consulted at The Royal College of Surgeons of England.

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    When we have a just idea of the signification of the terms erect anc inverted, it will not be difficult to discover that the perception of erect ness in an object involves a principle which is more elementary, anc which is not confined to vision. If we show that the same principle ex tends to the sense of feeling, we shall have advanced at least one stej in the investigation of this apparent anomaly. Now considered without any reference to the course or bearing oi our \mlimtary motions—i. e., reference to the particular direction ii| which the eye or hand is to be moved to trace it—an object appears erec or inverted only with reference to some other object, with reference M the earth for example, or with reference to the body of the observer. I I am conscious of being erect, and if I perceive another individual iij the same position with myself, I perceive him to be erect also. NovJ the obscurity in which the theory of the perception of position has ap, peared to be involved, has resulted from the confusion which has beeii introduced by comparing one object with the image of another, instead o comparing objects with objects, and images with images, or in othe words, from comparing the perception of one object with the sensation pro duced by the image of another, instead of comparing perceptions wif perceptions, and sensations with sensations. If I am standing, and man stands erect before me, I do not compare the sensation produced b; his inverted image with the perception produced by the inverted imag of my own body ; but I compare the sensations produced by the two images It is easy to conceive that our minds might be so constituted, that th impressions made on any two contiguous points of our organs of sens might be attended by a perception of contiguity in the objects, and ths distance between the points impressed—i. e., the intervention of intei L mediate points of the organ—might be attended with the perception c ^ distance between the objects. Surely no one can conceive any reaso ^ why an impression on two contiguous points should give a perception c remoteness. If it gives any perception of location, it must be that c contiguity. This, if a principle, would suffice for showing the correc ness of our earliest notions of the relative position of external objects 5^ But instead of viewing this as an ultimate principle, I derive it fror |j others more elementary, and consider the perception of angular distanc i, and in one sense that of contiguity, as dependent on muscular feeling maintaining, however, that after a very short experience, simultaneou impressions on contiguous points give a perception of contiguity, an ;;ij those on remote points a perception of remoteness, and that consequent! . it is impossible that erect objects could appear inverted when their part l,: are viewed either successively or simultaneously. To leave nothin 5,j vague, let us consider what is the fundamental idea of contiguity and a preliminary to it—of contact. If I place my finger so near an object a ].■, to feel its resistance, I touch it. This is my fundamental idea of cot' n tact, yet I can conceive that a closer proximity might be required in ordt| that a being differently constituted should receive the same sensatioi) and I believe that no two particles of matter are in absolute contac The above, therefore, is not absolute contact, strictly and mathematicall, considered, but it is physical contact, i. e., such a degree of approxinicj lion as produces onus a sensible repulsion. Now, to examine an object by the sense of feeling, requires conta<| with the organ of feeling. If I move my finger continuously along th| ^ surface of an object, so as to be in contact with its different points in su(| ■