96 



Dr. E. Rose on the Doctrine 



I scarcely need repeat that I have hitherto in vain confronted 

 some of these gentlemen — this time, for instance, F, G, J ; in no 

 case has the equation been the same for two patients. 



While a healthy or a colour-blind person seeks in vain for such 

 a colour-equation, a colour-mistaken person is ready in a minute. 

 A completely colour-mistaken person differs from the ordinary 

 singly colour-mistaken in the circumstance that the latter finds 

 an equality in only one position. For the former, the upper 

 Nicol may be placed as we like ; hy turning the bottom one 

 he effects an equation. Yet the reverse is not the case : the 

 lower arm cannot be turned beyond a certain difference of 

 brightness. 



Mr. L, for instance*, gave the following equations : — 



1. 



0- 



-10 



= XJ-56| 



19. 



10 + 



= U-61 



2. 



0- 



-20 



= U-61 



20. 



20 + 



= U-62i 



3. 



0- 



-30 



= U-63± 



21. 



30 + 



= U-64 



4. 



0- 



-40 



= U-66 



22. 



40 + 



= U-58i 



5. 



0- 



-50 



= U-58i 



23. 



50 + 



= U-53i 



6. 



0- 



-60 



= U-52i 



24. 



60 + 



= U-49 



7. 



0- 



-70 



= U-46i 



25. 



70 + 



= U-40 



8. 



0- 



-80 



= U~36| 



26. 



80 + 



= U-36 



9. 



0- 



-90- 



■ = U-32i 



27. 



+ 90 + 



= U-30± 



10. 







80- 



•=U-27 



28. 



+ 80 



= U-25i 



11. 







70- 



•=U-24 



29. 



O + 70 



= U-21i 



12. 







60- 



= U-20i 



30. 



O + 60 



= U-19i 



13. 







50- 



= TJ-22i 



31. 



+ 50 



= U-20 



14. 







40- 



= U-29i 



32. 



O + 40 



= U-24 



15. 







30- 



= U-36i 



33. 



+ 30 



= U-30| 



16. 







20- 



= U-45 



34. 



+ 20 



= U-38i 



17. 







10- 



= U-50 



35. 



+ 10 



= U-45J 



18. 







o± 



= U-57 



36. 



0± 



= U-54i 



nd Mr. 













37. 



+ 30 



= U + 34 



43. 



30- = 



= U + 28 



38. 



0- 



- 



= U + 57 



44. 



0+ = 



= U + 56|i 



39. 



0- 



-30 



= U + 57 



45. 



30+ = 



= U + 67" 



40. 



0- 



-60 



= U + 45 



46. 



60+ = 



= U + 52 



41. 



0- 



-90 



= U + 31 



47. 



90+ = 



= U + 34 



42. 







60- 



= U + 20 



48. 



+ 60 = 



= U + 22 



* The colour-measurer usually stands on the window-sill in such a man- 

 ner that the support is on the right hand, so as to be read off on the left. 

 The quadrant turned towards the observer I call the positive. If the mark 

 is on the right side of the observer, I place the number of degrees of the 

 reading on the right of (behind) the cipher, — for instance, O 24 — . 



