Roundel for use in optical experiments Size:XL: 80 x 80cm Two dogs are seen at

Two dogs are seen at left

View of Blackfriars Bridge and St Paul's Cathedral

1959 MGA Twin Cam

Bonaparte Crossing the Grand Saint-Bernard Pass

The Hippocanthus or Sea-Horse

Roundel for use in optical experiments Size:XL: 80 x 80cm Two dogs are seen atPlate 9 figure 2 from the paper "New experiments on the ocular spectra of light and colours", by Robert Waring Darwin, Philosophical Transactions of the Royal Society, vol. 76 (1786), pp. 313 348. Roundel intended for use in exploring colour perception. In the written experiment circular pieces of silk are overlaid in the sequence blue (outer), yellow, pink, green and indigo (inner) with a central spot. "look steadily for a minute on this central