DOI Page / Citation link:
https://doi.org/10.11588/diglit.1211#0029
25
frequently be at a loss, as I confess myself to have been, from want of clear
ideas on the subject; and the conviction that those must be obtained before
perfection could be arrived at, has been like a weight upon my pencil, pre-
venting its exertion, making me work without confidence or satisfaction, and
constantly in quest of the guide I wanted.
Lairesse proposes a method of coming at the point, by making use
of coloured patches of silk, or paper, and placing them before the eye in
gradual succession, giving precedence in order to those which struck the eye
first, and so on. And his method might answer, in a certain degree; but,
in many instances, it would leave the eye doubtful and undecided, and give
no information to the judgment, why such and such tints should be preferred
or placed in such or such situations.
But some late philosophical experiments appear to afford a surer test, as
far as they go, and promise, I think, a certain principle to act by*.
The experiments41 allude to, are those by Dr. Herschel, for ascertaining
the illuminating and heating power of the rays of the sun : those on the
power of illumination answer, in fact, to what Lairesse practised with the
coloured patches, only they were tried in a nicer manner with the microscope,
than could be with the naked eye; and are so exactly specified as to save
any one else the trouble of repeating the experiments. They determine the
situation of the colours in regard to each other; but the quantity of each
must either be determined by their respective heat or strength, or by the
prismatic proportions; possibly they may correspond: for though Doctor
Herschel does not specify all the experiments he tried as to heat, he says
* I have sought assiduously from books, &c. and have received information on many different
points from the practice of others: yet I have never met with any entire system or theory for the
arrangement of colours: and though I know the old masters took the rainbow for their guide, the,
little opportunity I have had of seeing their works, has prevented me observing how they availed
themselves of the lessons it afforded them. They also possessed a degree of philosophical knowledge,
that made them profit more speedily from their observations than any one can do without that know-
ledge; who must ignorantly copy nature, till some scientific person shall point out the way to do
it to advantage.
E
frequently be at a loss, as I confess myself to have been, from want of clear
ideas on the subject; and the conviction that those must be obtained before
perfection could be arrived at, has been like a weight upon my pencil, pre-
venting its exertion, making me work without confidence or satisfaction, and
constantly in quest of the guide I wanted.
Lairesse proposes a method of coming at the point, by making use
of coloured patches of silk, or paper, and placing them before the eye in
gradual succession, giving precedence in order to those which struck the eye
first, and so on. And his method might answer, in a certain degree; but,
in many instances, it would leave the eye doubtful and undecided, and give
no information to the judgment, why such and such tints should be preferred
or placed in such or such situations.
But some late philosophical experiments appear to afford a surer test, as
far as they go, and promise, I think, a certain principle to act by*.
The experiments41 allude to, are those by Dr. Herschel, for ascertaining
the illuminating and heating power of the rays of the sun : those on the
power of illumination answer, in fact, to what Lairesse practised with the
coloured patches, only they were tried in a nicer manner with the microscope,
than could be with the naked eye; and are so exactly specified as to save
any one else the trouble of repeating the experiments. They determine the
situation of the colours in regard to each other; but the quantity of each
must either be determined by their respective heat or strength, or by the
prismatic proportions; possibly they may correspond: for though Doctor
Herschel does not specify all the experiments he tried as to heat, he says
* I have sought assiduously from books, &c. and have received information on many different
points from the practice of others: yet I have never met with any entire system or theory for the
arrangement of colours: and though I know the old masters took the rainbow for their guide, the,
little opportunity I have had of seeing their works, has prevented me observing how they availed
themselves of the lessons it afforded them. They also possessed a degree of philosophical knowledge,
that made them profit more speedily from their observations than any one can do without that know-
ledge; who must ignorantly copy nature, till some scientific person shall point out the way to do
it to advantage.
E