the Inflection, Reflection , and Colours of Light . 237 
white was now to be seen ; and on moving the pin, the colours 
moved also. But they disappeared if the pin was deprived of 
its polish, by being held in the flame of a candle, or if a roll of 
paper was used instead of the pin ; also, they were much 
brighter in direct than in reflected light, and in the light of 
the sun at the focus of a lens, than in his direct unrefracted 
light. Placing a piece of paper round the hole in the window- 
shut, I observed the colours continued there ; and inclining 
the chart to the point where they left off, I saw them conti- 
nued on it, and then proceed as before to the shadow. If the 
pin was held horizontally, or nearly so, they were seen of a 
great size on the floor, the walls, and roof of the room, form- 
ing a large circle ; and if the chart was laid horizontally, and 
the pin held between the hole and it, in a vertical position, the 
circle was seen on the chart, and became an oval, by inclining 
the pin a little to the horizon. 
Ohs. 2. Having produced a clear set of colours, as in the 
last observation, I viewed them as attentively as possible, and 
found that they were divided into sets, sometimes separated 
by a gleam of white light, sometimes by a line of shadow, 
and sometimes contiguous, or even running a little into one 
another. They were spectra, or images of the sun, for they 
varied with the luminous body by whose rays they were 
formed, and with the size of the beam in which the pin was 
held; and when, by placing it between my eye and the 
candle, a little to one side, I let the colours fall on my retina, 
I plainly saw that they resembled the candle, in shape and 
size (though a little distended), and also in motion, since if 
the flame was blown upon, they had the like agi-ation. The 
colours therefore which fell on the chart were images of the 
