The student's guide to diseases of the eye . ively, by means of a light of known intensity, which passesthrough apertures filled by differently coloured glasses; theseare recognised at a specified distance if the colour-sense isnormal. Bull (of Christiania) has introduced a quantitative test,based upon the smallest amount of colour which, mixed withgrey, can be recognised by the normal eye (to be obtained fromTriibner and Co.) Rows of coloured spots, those in each rowcontaining a different quantity of grey, are paiuted in oil colourson a black back-ground. The normal eye will distinguish theco
The student's guide to diseases of the eye . ively, by means of a light of known intensity, which passesthrough apertures filled by differently coloured glasses; theseare recognised at a specified distance if the colour-sense isnormal. Bull (of Christiania) has introduced a quantitative test,based upon the smallest amount of colour which, mixed withgrey, can be recognised by the normal eye (to be obtained fromTriibner and Co.) Rows of coloured spots, those in each rowcontaining a different quantity of grey, are paiuted in oil colourson a black back-ground. The normal eye will distinguish thecolours even in the greyest row ; the colour-blind will, accord-ing to the degree of defect, confuse complimentary colours insome, or all of the rows. 1 find Bulls tables very useful butlike all painted and lithographed surfaces they reflect too muchlight, and thus, unless held exactly in the right position, theyshine and their colour is altered. Unless very carefully usedthey are, I think, less trustworthy than a good set of wools. 1 2 3 4 5. 7
Size: 2836px × 881px
Photo credit: © The Reading Room / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1800, booksu, booksubjecteye, booksubjectophthalmology
