relating to the
Vision of Colours:
BY MR. JOHN DALT0N.
HEAD OCT. 31ST, 1794.
MX has been observed, that our ideas of colours,
sounds, tastes, Sec. excited by the same object may
be very different in thettlselves, without our being
aware of it; and that we may nevertheless converse
intelligibly concerning such objects, as if we were
certain the impressions made by them on our minds
were exactly similar. All, indeed, that is required
for this purpose, is, that the same object should
uniformly make the same impression on each mind;
and that objects which appear diffeitnt to one should
be equally so to others - It will, however, scarcely
be supposed, that any two objects, which are every
day before us, should appear hardly distinguishable
to one person, and very different to another, without the circumstance immediately suggesting a difference in their faculties of vision; yet such is the fact,
not only with regard to myself, but to many others
also, as will appear in the following account.
I was always of opinion, though I might not of-