794 



SCIENCE. 



[N. S. Vol. VIII. No. 205. 



hope that the shorter word of Aristotle may 

 find favor with Mr. Willey. 



BuET G. Wilder. 

 Ithaca, N. Y., November 18, 1898. 



POST-GLACIAL CONNECTICLTT. 



To THE Editok op SCIENCE : A note in your 

 issue of the 28th ult. makes my ' Postglacial 

 Connecticut at Turner's Falls,' in the Chicago 

 Journal of Geology (July-August), ' invoke the 

 agency of ice ' to cut the abandoned gorges at 

 the Bird Track Quarry and Poag's Hole. This 

 is just only in so far as it is true that had there 

 been no glacier there would be no postglacial 

 superposed gorge. The gorge, like all those of 

 its class, was cut by the river and a clear photo- 

 graph is reproduced, showing the visible water 

 wear on these rocks in a region where all others 

 are beautifully rounded by glaciation. 



Makk S. W. Jefferson. 



Brockton, Mass., November 11, 1898. 



SCIENTIFIC LITER ATVBE. 

 Handbuch der physiologischen Optik. H. voN 



Helmholtz. Hamburg und Leipzig, Leopold 



Voss. 1896. Second Revised Edition. Pp. 



xix+1334. M. 51 ; Bound, M. 54. 



The phenomena of vision are so far-reaching 

 and at the same time so organically related that 

 they may almost be regarded as the subject- 

 matter of a separate science. It is neither pos- 

 sible to include them under physics, under 

 physiology or under psychology, nor to distrib- 

 ute them among these sciences. The photo- 

 chemistry of the retina, the anatomical and 

 histological data, and the comparative and evo- 

 lutionary relations, add still further to the range 

 of the subject. On vision is based one of the 

 more important departments of medicine; for 

 ophthalmology can in most cases not only offer 

 a correct diagnosis, but also a cure. Probably 

 a majority of the whole population needs 

 its services, and if we add the hygiene of 

 the eye, including the proper lighting of 

 schools, the proper printing of books, etc., 

 there is no one to whom the scientific study 

 of vision is not of practical importance. The 

 phenomena of vision are further factors in the 

 production and appreciation of the great plastic 

 arts — painting, sculpture and architecture. 



Finally, the world in which we live is before all 

 the world we see. 



If there be a science of vision, von Helmholtz 

 should be honored as its founder, and it should 

 date from the completion of the Physiologische 

 Optik in 1867. It is true, the doctrine of special 

 creations belongs to the past. Like other de- 

 partments of knowledge, vision has had a long 

 history and a gradual development, von Helm- 

 holtz found at hand not only the greater part of 

 the materials for his structure, but also many of 

 the designs. From the side of physics he had 

 the series of contributions from Kepler, Des- 

 cartes, Newton, Lambert, Young, Brewster ; 

 from physiology there were Haller, Priestley, 

 J. Miiller, Plateau, Volkmann, Purkinje; from 

 philosophy Berkeley ; from art da Vinci and 

 Goethe — to mention but a few of many names. 

 Contemporary with von Helmholtz worked 

 Aubert, Hering, Listing, von Graefe, Briicke, 

 Vierordt, Bonders, von Bezold and many 

 more. But of them all von Helmholtz alone 

 saw the range and unity of the subject, and 

 prepared one of the few books that make an 

 epoch. So well was his work performed that it 

 has scarcely had a successor — only Aubert's 

 Orundzuge der physiologischen Optik deserves to 

 be mentioned— and it remained for von Helm- 

 holtz himself, in old age, with energies diverted 

 to other channels, to write a new edition of his 

 great work. 



To give in a review an account of the con- 

 tents of a book extending to 1,300 pages, writ- 

 ten with great conciseness and covering a range 

 of subjects so wide, is evidently infeasible. 

 Still less possible would it be to enter into crit- 

 ical discussion — an article might be written on 

 each of a hundred topics. This notice must be 

 confined chiefiy to the new edition, and the 

 eulogy appropriate to the first edition must be 

 tempered with criticism. 



Publication of this edition was begun in 1888. 

 In the course of about a year three parts were 

 issued, treating of the anatomy and dioptics of 

 the eye. About forty pages are here added in 

 addition to substitutions for material omitted 

 and thorough revisions throughout. The pages 

 in the new edition are, however, somewhat 

 smaller than in the old. This Section concludes 

 with the description of von Helmholtz' s great 



