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XLVIII. Intelligence and Miscellaneous Articles. 



ON A SINGULAR IRREGULARITY OF VISION. 

 BY N. S. HEINEKEN, ESQ. 



To the Editors of the Philosophical Magazine and Journal. 



Gentlemen, Sidmouth, Sept. 2, 1848. 



CHANCE has thrown in my way an extract from the Medico- 

 Chirurgical Review for 1834, in which it is stated that M. Pre- 

 vost of Geneva and Mr. Babbage have themselves experienced a 

 singular irregularity of vision, viz. that of double images with one 

 eye. The details are given in the work above-named, and also in 

 the Arcana of Science for 1834, p. 184. 



I am induced to trouble you with this communication in order to 

 make known a somewhat similar irregularity in my own case ; though 

 as mine was only temporary, it may perhaps, from the circumstances 

 under which it occurred, afford some clue to the cause. I therefore 

 forward the following note, made at the time, for your perusal. 



" Having occasion to divide a yard into a thousand parts, I used 

 an eye-lens of six inches focus to assist the right eye while dividing 

 — the left was kept closed. I had been employed about two hours 

 in making 400 divisions, and then left off. I then found that upon 

 looking at a window on the opposite side of the street with the left 

 {unemployed) eye, the bars were triple, while with the right (em- 

 ployed) they were single. This effect lasted (gradually decreasing) 

 for at least two hours ; the bars were also surrounded by a strong 

 penumbra. At first, objects — such as people on horseback — were 

 so distorted that I had great difficulty in deciding what they 

 were." 



On another occasion I have noticed a defect of vision of a some- 

 what different character, of which I also send you the note made at 

 the time. " Upon rising one morning I observed in the right eye, 

 as it were, innumerable faint scintillations or lucid points, the whole 

 field of vision being covered by them. Upon going to a looking- 

 glass, I found that I could not see one half of the face with that eye 

 — it appeared perfectly dark. The effect lasted perhaps half or 

 three quarters of an hour." Dr. Kitchener mentions having been 

 alarmed by a somewhat similar appearance ; but this seems to have 

 arisen from over-exertion of the eye from minute examination of the 

 powers, &c. of several telescopes. In my own case, I am not aware 

 that the eye had been at all overworked on the previous day, or for 

 some length of time; nor had it any connexion with the previous cause 

 of multiple vision, this having occurred more than twelve months 

 before. If you deem the above at all likely to interest your readers, 

 I hope you will make use of it. 



I am, Gentlemen, 



Respectfully yours, 



N. S. Heineken. 



