June 17, 1904.] 



SCIENCE. 



919 



B. horeale, of which several collections have 

 now been made from Alaska. 



While the work as a whole would impress the 

 average non-botanical reader as a list of plants 

 merely, only those who have been engaged in 

 distributional studies will understand the im- 

 mense amount of careful and critical labor in- 

 volved in the study of the material that under- 

 lies its preparation. It may be too early to 

 form any general conclusions regarding the 

 relations of the Alaskan flora, and it may be 

 that the editors are expecting to include this 

 in a later account in the two forthcoming 

 volumes on the Spermatophytes which are ex- 

 pected ' in the early part of 1904,' but we are 

 disappointed only in the absence of some more 

 general discussion of the relations of the 

 Alaskan flora to other regions. 



The mechanical execution of the work is a 

 great credit alike to the projector of the ex- 

 pedition, to the editors, and to the publishers. 

 The heliotype plates are especially flne. 



LuciEN M. Underwood. 



Columbia University, 

 May 19, 1904. 



The Eye, its Refraction and Diseases. By 

 Edward E. Gibbons, M.D. 19 x 23 cm., pp. 

 ix + 472, index. New York, The Macmillan 

 Company; London, Macmillan & Co., Ltd. 

 1904. 



The English-speaking student of ophthal- 

 mology whose special desire is to cultivate 

 that subject as a useful art, has been much in 

 need of a manual which should concern itself 

 especially with the science of optics, geomet- 

 rical and physiological, as applied in practise, 

 such application being nowadays an impor- 

 tant part of the daily routine work of the 

 oculist. 



A few years ago the elegant little ' Hand- 

 book ' of Suter appeared, giving what was 

 necessary in a geometrical line, and a short 

 time after that Tcherning's ' Physiological 

 Optics ' was translated. Much of the subject 

 matter of these two books necessarily enters 

 into this volume of Dr. Gibbons, but much 

 else has been included, sometimes in a cursory 

 way, yet one finds here an excellent manual 

 for the student or physician who thinks 



Landolt a little stiff for the first bout, and 

 wishes the encouragement of the colloquial and 

 sympathetic. If one expects in this volume 

 any consideration of, or allusion to, the in- 

 flammatory affections with which text-books 

 on 'Diseases of the Eye' are often almost ex- 

 clusively concerned, he will be disappointed. 

 Only by a liberal construction of the word 

 disease to include refraction anomalies and 

 muscular insufiiciencies can the contents of 

 the book be made to justify the title page. 

 The author need not be censured for thus 

 limiting his subject matter. Conditions of 

 the art and of the market make it desirable 

 that just this ground should be covered in very 

 much this way. But the title of the book is 

 misleading. 



The first seventy-five pages are taken up 

 with geometrical optics. In order to appre- 

 ciate this part, one must know that the au- 

 dience addressed is entirely made up of med- 

 ical men, and that the subject matter of the 

 address is purely mathematical. Young men 

 who have ability and predilection for mathe- 

 matics rarely choose medicine as a profession, 

 and most physicians shy at any kind of a 

 formula that can not be put up by a druggist. 

 Yet a man who wishes to be an oculist finds, 

 after six or eight years devoted to a science 

 not particularly formal, that he is face to face 

 with a well-developed mathematical specialty, 

 and he is lucky if he remembers enough of his 

 undergraduate work to help him through. An 

 occasional one will regard this situation as 

 refreshing — he will write the book. More 

 will accept it with resignation, and ask for 

 what they miscall a ' practical ' knowledge of 

 the subject, obtained by means of diagrams 

 and illustrative cases with very little of the 

 condensation and generalization attractive to 

 the former. It is the delicate task of the 

 author to give the reader all he needs of the 

 one, and a little more than he thinks he needs 

 of the other. The indispensable in this case 

 is just so much of the theory of centered 

 optical systems as will enable one to combine 

 the three principal refracting surfaces of the 

 eye with two others belonging to any spectacle 

 lens that the patient may wish to wear, and 

 to calculate the place of the cardinal points. 



