INTRODUCTION. 
That philosophers and artists liavc long wished for some never- 
fading colours to fix their ideas and universalize them, is in every 
age anij)ly verified ; and as coloured substances, like all other sublu- 
nary things, are liable to a certain decay, so it has been but weakly 
attempted lately; besides, the dilVicuIty of finding a means of agree- 
ment in the modifying and arranging them has been a desideratum, 
as late works have abundantly, showed. Enamel, perhaps, is as 
durable as any substance, and has with much jiropriety been pro- 
posed; but the uncertainty of an ability to procure an equality 
throughout a single tint, puts us nearly in the same predicament as 
with other coloured schemes. This vve shall find true in our attempt, 
as will be too evidently seen in the present examples. We presume 
our method of arranging will much assist both the colours and the 
mind, and even this scheme might be desirable in enamel or glass 
for the sake of durability; but 1 may question even if the best ena- 
meling artists can place colours so well, (which in no way degrades 
their greater merit,) as it is seldom they have occasion for the ex- 
perience of an object so trifling to the best of such ailists*. 
Upon the whole, the necessity of supplying this desideratum 
need not be dwelt upon, as the numerous attempts to do it are a 
suflicient acknowledgement, and argue much for its utility. In my 
researches it has luckily fallen to my lot to find one resource or 
monitor in Nature, which is as constant as the light from which it is 
deduced, and the regularity or certainty depends upon very simple 
materials. 
The use of a true original for colours, and a regularity of arrange- 
ment, is almost infinite; for to the artist in any line it will be a 
solid satisfaction to know when he treads on a sure foundation, laid 
by unerring Nature. The mineralogist, the botanist and the zo- 
ologist may in future agree in their descriptions and ideas, so as to 
identify them to all parts of the world, and the remotest ages. 
* Perhaps it may succeed somewhat in transparent oil, but water colours are most 
convenient for a book. 
