EYE AS A CAMERA OBSCURA. 329 
That the eyes of living men and women emitted light, and shone like those of 
the cat, had been occasionally noticed and recorded from an early time, but the 
phenomenon was supposed to be an exceptional, and indeed very rare one, and 
was either credulously magnified into a highly marvellous occurrence, or despised 
as of questionable accuracy, and of little real significance. In (or about) 1847, 
however, Mr Cummine, an English medical practitioner, pointed out that the phe- 
nomenon in question might be witnessed in every human eye, if looked for in the 
right way; and a little later and independently, Briicxr made the same discovery 
in Germany, through the curious circumstance, that occasionally when looking 
through his spectacles, at the face of another, he saw his neighbour’s eye glare like 
a cat’s. 
In 1851, the accomplished physiologist and natural philosopher of Koenigs- 
berg, HeLMHoLTz, showed how the observation which Brijcxe had made accident- 
ally, might be repeated at will; and carrying out the principle thus established, 
constructed an eye-speculum which soon proved a most valuable addition to the 
diagnostic apparatus of the oculist. Other eye-specula or ophthalmoscopes were 
devised or improved by RueteE and Coccius of Leipsic, ANaGNosTaKIs of Athens, 
and the English opticians, and are now in use in the hospitals of this country 
and the continent. It will be sufficient for me, therefore, to give in a note, the 
names of some of the chief works from which those to whom the subject is new 
may obtain information regarding eye-specula; especially as no more complex 
‘instrument. than a fragment of polished glass, or of perforated polished metal is 
required to show that light is reflected from the bottom of the eye; and even this 
is only needed to facilitate the observation; for by following Mr Cummine’s direc- 
tions the fundamental phenomenon may be witnessed without the employment 
of any refiector.* 
The demonstrability of the proposition, that the eye is not a camera obscura, 
* Cummine’s observations are contained in Medico-Chir. Trans., Lond., vol. xxix., p. 283; 
Bricxe’s, in Miixzizr’s Archiv., 1847, p. 225. 
Hetmuorrz’s description of his speculum occurs in a little work, entitled, “« Beschreibung eimes. 
_ Augen-Spiegels zur Untersuchung der Netzhaut in lebenden Auge. Berlin, 1851.” An excellent 
abstract of this paper by Dr W. RB. Sanpers, accompanied by comments of his own, will be found in 
the Edinburgh Monthly Journal of Medical Science, July 1852, p.40. Iam indebted to this gentle- 
man for my knowledge of Hutmnoxrz’s instrument, and for the opportunity of using it. , 
_ The eye-specula of Ruzre and Coccrus, as well as of Hetmuorrz and others, are described in a 
work, entitled, “ Bildliche Darstellung der Krankheiten des Menschlichen Auges, von Dr C. G. T. 
Ruere; 1 and 2 Lieferung: Leipzig, 1854.” Professor Rurrx’s beautiful work contains a series of 
coloured drawings, representing the internal structures of the eye, as seen under the speculum. 
Since this paper was read to the Society, a valuable communication on the medical employment 
of eye-specula has appeared in the British and Foreign Medico-Chir. Review for April 1855 (p. 501 ) 
It is entitled, “ On the Means of Diagnosing the Internal Diseases of the Hye. By C. Bape, M.D., 
and Branssy Roszerts, Esq., Resident Medical Officer, Royal London Ophthalmic Hospital, Moor- 
fields,” and contains the fullest and most recent account of eye-specula accessible to English readers, 
with a record of observations made on healthy and diseased eyes. From this paper, I have borrowed 
the use of the word Ophthalmoscope, used occasionally in the text. 
