of the Harmony of Colours. 69 



other with a powder composed of white lead and lamp- 

 black, in such proportions that the quantities of light 

 reflected from the two slips so prepared should be 

 equal, I placed these slips in contact with each other, 

 in the middle of the circular piece of paper on the 

 floor ; when retiring backwards a few steps, and look- 

 ing through my hand with one eye, to exclude all 

 other objects, I had the pleasure to perceive that the 

 slip of paper which was covered with a gray powder 

 now appeared to be of a beautiful greenish blue colour, 

 while the other was of the most vivid red. 



This experiment was first made at an inn at Flor- 

 ence, in the year 1 793 ; and in order that I might 

 assure myself that my expectations had not deceived 

 me, by imposing upon my senses, I called two of my 

 friends who happened to lodge in the house (Lord and 

 Lady Palmerston) into the room, and without letting 

 them into the secret simply asked them, with a feigned 

 air of indifference, which of the two colours they saw 

 in the centre of the circular piece of paper on the floor 

 they thought the brightest. 



After looking at them for some time, and going 

 round to view them from different sides, one of them 

 answered : " I don't know which of them is the bright- 

 est. The red is very bright, and so is the blue. But 

 why do you ask us that question ? " 



When I told them there was no blue there, and that 

 what they took to be blue was merely a deception, they 

 did not believe me ; but they were much surprised, and 

 convinced that what I told them was true, when they 

 saw on my removing the red slip that its companion, 

 which was left behind, instantly faded and lost its 

 colour. 



