An essay upon single vision with two eyes : together with experiments and observations on several other subjects in optics / by William Charles Wells, M.D.

  • Wells, William Charles, 1757-1817.
Date:
1792
Catalogue details

Licence: Public Domain Mark

Credit: An essay upon single vision with two eyes : together with experiments and observations on several other subjects in optics / by William Charles Wells, M.D. Source: Wellcome Collection.

Provider: This material has been provided by University of Bristol Library. The original may be consulted at University of Bristol Library.

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    ' ( Hi )' eye Wilr now fee an object diitindtly,; which' is only about feven inches from it,' and my right eye will at the fame time fee ah object diftinctly, the diftance of which is about ten inches. I find alfo, that my left eye is made to fee aft object] diflindtly; though placed more than nineteen inches from it, if I direct both axes to a point ftill more remote. 2. I formerly mentioned, that every degree of the mutual inclination of the optic axes is attended, by a particular ftate of the refracting power of each eye. But I muft. now remark, that thefe ftates are fometimes fubject to flight variations, while the inclinations of the optic axes to each other remain the fame. For I find, that, when a luminous point, to which both axes are turned, is diftindtly feen by my left eye, I can, by certain efforts not eafily to be defcribed, but without changing the pofition of either axi.% make it afterward appear as a furface, and this too, at one time, from the rays coming to a focus too fuon, and at another, too late, for perfect T vifioft