piderat 
XXI. On the Work entitled Chromatics ;” or, An Essay ont 
the Analogy and Harmony of Colours. By Mr. 'T. Har- 
GREAVES. 
To Mr. Tilloch. 
Sir, — In your last Number you mentioned the publication of 
“* An Essay on the Analogy and Harmony of Colours.”? On 
turning over a copy of it, which I have now by me, I remark, 
that not only are the coloured diagrams incorrect, but that they 
are at variance with the observations which accompany them. 
In pointing out this incorrectness, it is not my intention to de- 
preciate the work, but to give the author an opportunity in a 
future edition of rendering it more perfect, should he consider 
my remarks deserving of his notice. My cebjection lies against 
that part of his work in which he treats on the particular rela- 
tions of colours. His first example of the white, black, and 
gray is correct; and in the second, I merely cbject to the co- 
lours employed for showing the three primaries, as not precisely 
giving the tenes required:—the ultrantarine inelines rather to 
purple ;. the Indian yellow to orange; and the red in its darker 
shade to orange. But perhaps these colours have been adepted 
for their durability. 
My principal objection is against the compound or derivative 
tints, given under the denominations of seconduries and tertiaries. 
But before | proceed, it may be proper to transcribe two or three 
passages from the work, which are in themselves perhaps unob- 
Jectionable, but with which the examples given are at variance. 
In section 8 he says: ‘‘-By the union of these three positive 
colours (red, yellow and blue) in due subordination, they are 
neutralized,” &c. — In section 24 “ Perfect neutrality depends, 
however, upon « due subordination of the primary colours: in 
which tue predominates in proportion to the depth of the eom- 
pound, and yellow is subordinate to red,” &e. Again, in sec- 
tion 21, ‘As the neutralization or negation of colours depends 
upon the reunion of the three primaries, if is evident that each 
of the primary colours is neutralized by that secondary which is 
composed of the two other primaries, alternately; thus, blue is 
neutralixed or extinguished by orange, red by green, and yellow 
ly purple.” . 
_ Considering all this as correct, and examining the coloured 
examples of the secondaries and tertiaries, with reference to 
these principles, they will be found to vary considerably. 
_ In the first place, the secondary or intermediate colour ‘of 
purple, ought to be such a combination of red and blue, in which 
the blue should predominate, as when combined with yellow 
should become completely neutralized. But on looking at the 
Example, 
