112 M. NOBILI ON COLOURS, AND ON A NEW CHROMATIC SCALE 
least but such as are extremely slight in comparison with those whiclr 
take place in the group of tints formed about the violet No. 11. There 
is no other fact connected with this. Such at least is my opinion, after 
having examined it under various aspects without being able to arrive 
at a satisfactory explanation. I am therefore unable to say more about 
it for the present. 
Effect of Artificial Light during the Night. 
It is an admitted fact, that we cannot judge of colours without the 
presence of daylight. But what changes do they undergo when viewed 
in the evening? The following are those that I have observed in the 
tints of my scale when examined at that time. The two conflicting opi- 
nions of those whom I consulted on this subject I forbear to mention. 
. The greens increase in beauty and intensity. 
. The yellows and the azure are tarnished and become deeper. 
. The blues and the indigo become greenish. 
- The violets approximate to a blue. 
- The violet-reds become more violet. 
- The first eight tints of the scale become more like each other, 
and approach more nearly to the metallic colours. 
. The other tints remain nearly unchanged. 
IT AoPonwe 
Some of those changes are produced even by day if the colours of 
the scale are viewed through a green crystal, and others if they are 
viewed through yellow or azure crystals. Artificial light is without 
doubt differently constituted from that of the sun: it contains pro- 
bably a scanty mixture of red rays with an abundance of the yellow; 
green, and azure. But what is the coloured diaphragm that should be 
interposed in the passage of the light of day, in order to reduce it to 
the same proportions as that of night? The problem is an interesting 
one, but it remains as yet without solution. 
Harmony of Colours. 
My scale appears to all persons to be eminently harmonious. I have 
already mentioned the delight which it afforded those who saw it. I 
have now to add that artists are astonished not to find the green in its 
usual place, between the yellow and theazure colours of the second order. 
But I take the two finest greens in the scale, Nos. 32 and 41, and call 
upon the most accomplished artists to assign them a more suitable place 
than that which they occupy. Influenced by habit they unhesitatingly 
place them among the yellows and the blues of the second interval, hay- 
ing no doubt that this is their proper place. They are however soon un- 
deceived by the result ; the green is found unpleasing here ; the harmony 
is destroyed, and cannot be re-established until the colours are restored 
to their original position. But what is this harmony? It is an effect 
