May 



•] 



SCIENCE 



2 1 7' 



Economic Cooking adapted to Persons of Moderate and Small 

 Means ; ' first prize to be $500 ; second prize, $200. All essays 

 written for the above prizes must be in the hands of the secretary. 

 Dr. Irving A. Watson, Concord, N.H., on or before Oct. 15, 1888. 



— Dr. William Noyes contributes to the Journal of Social Science 

 (No. xxiv.) a convenient summary of the modern view of the crim- 

 inal type. Taking Lombroso as his guide, he shows in how very 

 many respects the criminal presents abnormal differences, both 

 physical and psychic, from his fellow-men. These differences are 

 to a large extent indicative of a reversal to a more primitive, savage 

 type. It is hopeful to add, that many of the peculiarities can be 

 detected in children, and that the evil results which they forebode 

 can be to a large extent prevented by a properly directed education. 



— At the March meeting of the Society of Medical Jurisprudence 

 and State Medicine of New York the best method of executing crim- 

 inals was discussed. Dr. William A. Hammond advocated stran- 

 gulation by a silk or cotton rope as the most satisfactory method at 

 command. He criticised the recent report of the State Commis- 

 sion, which recommended the use of electricity, and said that the 

 objections raised against the present method of execution would 

 apply with equal force to any form of execution. Several of the 

 members took exception to Dr. Hammond's statement that stran- 

 gulation was painless, and Drs. Spitzka and Brill spoke in favor of 

 the guillotine. The society finally adopted, by a nearly unanimous 

 vote, a resolution condemning the bill now before the Legislature, 

 which embodies the recommendations of the State Commission re- 

 ferred to, an abstract of which has already been given in Scie?ice. 



LETTERS TO THE 



EDITOR. 



*,* Correspondents are requested to be as brief a 

 in all cases required as proof of good faith. 



spos 



sible. The writer s name is 



Twenty copies of the number containing his ct 

 free to any correspondent on request. 



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The editor 'will be glad to publish any queries 

 the journal. 





■onant with the character of 



Experiments in Vision Again. 



Some time since in Science (No. 262) we referred to an experi- 

 ment which we thought indicated an interesting connection between 

 monocular and binocular vision. We have another to present here 

 which seems in our own experience to possess a similar importance. 

 It is perhaps even more forcible than the first, and may be worth 

 the attention of those interested in visual phenomena. 



Take two circles as represented in Fig. i, and either bend the 

 sheet of paper in the median plane, so that the circles can be made 

 to appear in inclined planes at any desirable angle, or cut the paper 

 so that they may be held at a suitable inclination to each other in 

 planes that will intersect at any given point. The larger the cir- 

 cles, the better will be the effect, the more clearly marked will be 

 the results we have to describe. Now, if we incline the planes of 

 the circles several degrees, it is well known that the retinal impres- 

 sion becomes ovular or elliptical ; and the circles also will appear 

 more or less so, when we make allowance for the judgments of 

 experience which can recognize a real circle, although the impres- 

 sion is not identical with it in form. If, then, we combine the cir- 

 cles by convergence at this slight inclination, the central and fused 

 image will retain its slightly elliptical form, although the surface 

 upon which it appears seems a plane vertical to the median plane. 

 The real inclination of the two surfaces does not appear to deter- 

 mine any irregularities in the effect ; but binocular agencies, perhaps, 

 balance the two opposing influences from monocular vision so as to 

 present the appearance of a plane. But if we increase the inclina- 

 tion of the two circles and their planes, say each of them to 45" 

 from the horizontal meridian, and cutting the median plane so as to 

 form a right angle with each other, and then combine them by con- 

 vergence, the effect may be entirely changed. We find that rivalry 

 may take place between the monocular images, and that there is a 

 tendency to see only one of the images at a time, of those belonging 

 to corresponding points. Not only does the circle appear elliptical, 

 but its plane appears in its real inclination to the median plane ; 

 that is, the circle seems to lie in the third dimension, with one side 



nearer the observer than the other, precisely as it ought to appear 

 in case that vision presents the real relations in space of its objects. 

 This effect may alternate from one inclination to the other, showing 

 that there is rivalry between the monocular images for expression 

 in the field of vision. Fatigue may cause this alternation. But the 

 interesting fact to be noted is, that binocular influences no longer 

 avail to make the plane of the fused images lie in plane of the hori- 

 zontal meridian. The circle seems inclined to this, and is seen in. 

 its real space relations, corresponding exactly to the innervation for 

 the individual eye which sees it. If we may ever speak of monocu- 

 lar influences suppressing those of binocular action, we may do so- 

 in such cases as these. 



We have been able also to obtain more complicated results of 

 the same general kind. This we accomplished by the use of stereo- 

 scopic figures, as in Fig. 2. The experiment is performed as before.. 



If placed at the proper inclination, and combined by convergence,, 

 we may notice the inclination of both circles ; that is, the monocular 

 images of one concentric set. The same alternation can be ob- 

 served as before. But by careful practice we have been able to 

 notice the larger circle inclined in one way to the median plane, and 

 the smaller in the opposite way. This makes the planes of the 

 larger and smaller circles of the apparently fused image appear to 

 cut each other at an angle instead of lying in the same plane. This 

 can be explained by supposing that the monocular image of one 

 circle is seen by the right eye, and the monocular image of the other 

 by the left eye. And as each appears to be in the plane in which 

 it really exists, the two must appear to cut each other at an angle. 

 Various alternations may be observed, besides those mentioned in 

 Fig. I ; but they are due merely to the larger number of circles and 

 the different possible relations represented. The results are es- 



pecially interesting as calling attention to and illustrating the fact 

 that binocular disparate points in their visual activity functionate- 

 precisely as monocular disparate points. This is simply another 

 way of expressing the phenomena of rivalry; for we observe in these, 

 that one area of the right eye may be acting in one way while the 

 corresponding area of the left is inactive, and a disparate area of 

 the left may be acting in another way while the corresponding area 

 in the right is inactive : hence the functional activity of one eye in 

 regard to the larger circle will not prevent the action of the other 

 eye in regard to the smaller circle of Fig. 2. In this case the sup- 

 pression of one of the binocular images in each case would leave 

 the visual process entirely to monocular functions ; and hence, 

 when the inclination of the real planes is great enough to be noticed, 

 it is quite possible that the effect would represent the two circles in 

 different planes cutting each other. It has required much practice, 

 however, to get the results we have described, as the easier tenden- 

 cy, when any inclination of the circles is observed at all, is to per- 



