158 PROFESSOR WARTMANN ON DALTONISM, 
I propose, in this Memoir, to cast a rapid glance over the 
principal facts of this second class hitherto known. Reserving 
the term Chromopsis for those cases in which colours are per- 
ceived in an extraordinary manner in consequence of a change 
of health, I shall apply to that in which the affection is natural 
the name of Daltonism, proposed by Professor Prevost, because 
the illustrious natural philosopher Dalton has described, as ex- 
isting in his own case, many particulars of it*. I shall adda 
description of new observations made under very favourable 
circumstances ; and, after a critical review of the explanations 
proposed by the various physiologists who have attended to this 
subject, [ shall conclude with an enumeration of some conse- 
quences to which the study of it may lead. 
It will perhaps be found that I have given too great an ex- 
tent to the historical part of this work ; but the absence of docu- 
ments in our language on a subject so interesting, and the desire 
that the observations here recorded may save persons disposed 
to study the subject the labour of going back to the sources 
which treat of it, will, I hope, serve as my sufficient excuse. 
* Professor Whewell is mistaken in attributing to me the choice of this de- 
nomination; I preserve it to avoid introducing a new ove, whilst I quite agree 
with him, that few persons desire to be immortalized by their imperfections, 
and that Dalton, above all others, has no need of such a means of trans- 
mitting his name to posterity. (See Atheneum of August 28, 1841, No. 722, 
p- 699.) For the rest, I think with an illustrious natural philosopher (Sir D. 
Brewster), who has given a review of The Philosophy of the Inductive Sciences, 
written by the learned Master of Trinity College, that the term Jdiopts, by 
which Mr. Whewell designates the Daltonians, is by no means a happy one. 
(Edinb. Review, January 1842, p. 266.) Nearly forty years ago the deno- 
mination Daltonian was employed in the oral instruction in the Academy of 
Geneva. Pierre Prevost printed as follows in 1827, in the Bibliotheque Uni- 
verselle: ‘The subject, whose vision he has described, appears to differ from 
the great number of those whom I am accustomed to call daltonians only by a 
slight degree of darkness in the shades.”—Tome xxxv. p. 321. And further 
on :—‘ On this statement...-.. I do not hesitate to pronounce him a Daltonian.” 
—Ibid. p. 322. 
[Nore.—Sir David Brewster, in his remarks on this memoir (Phil. Mag. for 
Aug. 1844, p. 134), expresses his regret that the author should have continued 
to employ this term, which he censures as degrading to the venerated name of 
Dalton, and faulty in regard of nomenclature. It is with reluctance that the 
Editor becomes accessary to the retention of this objectionable denomination, 
for which he would have much preferred to substitute Parachromatism, Para- 
chromatic, &c., derivatives of raeuyeawups, raoaxowgsc, &c., as designating 
generally the fact of perversion of colour; but he is advised that such a change 
would be beyond the province of a translator. He has, however, ventured to 
add, in the title merely, the term Colour Blindness, adopted by Sir David 
Brewster. Dyschromatopsis, Pseudopsis and Heteropsis have been suggested ; 
but the two latter are not sufficiently specific— Ep. ] 
