714 



SCIENCE. 



[N. S. Vol. XI. No. 27&. 



medical authorities ; but I know of no attempt 

 to figure the appearance in the field of vision. 

 Subjoined I give figures showing my own visual 

 modification in three stages — initial, maximum 

 and final — with the location and local progress 

 of the symptom, taken during an attack last 

 summer, after freedom from the headaches for 

 years. It was brought on probably by the 

 glittering effect of the sun on the water in sea- 

 bathing, an inducing cause sometimes noticed 

 by other observers, and rather frequent in the 

 period of boyhood and youth in my own case. 



The area covered by the peculiar net-work 

 shown in the figures is bright light-gray and 

 the configuration itself is of the appearance of 

 water-bubbles or divisions. The lines are all 

 straight and at right- angles to one another. 

 The progress of the stigmate, if that term be 

 allowed, is interesting from the point of view 

 of theories of the localization of the trouble in 

 the brain. The initial appearance covered the 

 left half of the hand held eighteen inches before 

 the face ; it gradually spread leftward and up- 

 ward (never downward or rightward) until it 

 covered the whole hand when the gaze was 

 fixed a little to the right of the hand and on the 

 line of its lower edge. It then travelled off the 

 hand by contracting upward and leftward (as 

 shown in Fig. 3). This would indicate that 

 the disturbance began in the right half of the 

 visual area (occipital lobe) of the right hemi- 

 sphere, or in the corresponding subcortical cen- 

 ters or tracts, spread over the entire upper half 

 of that area (left upper quadrant of the field of 

 visions), then died away progressively in the 

 same order, this inference depending, of course, 

 on the hypothesis of a projection of the elements 

 of the visual area upon the retina. 



It is interesting from the psychological point 

 of view to note that a strong and persistent ef- 

 fort to call up the appearance, as for drawing a 

 figure of it or describing it, produces in my 

 case positive sensations of nausea. 



J. Mark Baldwin. 



Oxford, January 20, 1900. 



THE DEVELOPMENT OF PHOTOGEAPHIC PLATES 

 IN THE LIGHT. 



It may be of interest to your readers to know 

 that if photographic plates in a camera are 



greatly over-exposed they may be developed in 

 the light. A plate which should for ordinary 

 work have an exposure of a second and a half 

 for street or outdoor photography may be ex- 

 posed for two hours. When developed with a 

 weak hydrokinone by the light of a lamp, it 

 gives a beautiful positive. The lamp is prefer- 

 able because one can manage the degree of il- 

 lumination. If the plate is held too near the 

 lamp it will dissolve a picture already appearing. 

 If held too far away the plate begins to fog. 

 By moving toward or from the lamp the proper 

 illumination may be soon secured. It is re- 

 markable that a street scene taken in this way 

 shows not a moving thing on the streets. Street 

 cars passing every two minutes, wagons, horses, 

 pedestrians, all have apparently vanished with- 

 out leaving a trace upon the plate. But the 

 fixed objects are shown perfectly, with their 

 proper shadows and high lights. 



In this way lantern slides and transparencies 

 may be made directly without re-photographing 

 from a negative. 



Francis E. Niphee. 



THE TOPOGRAPHIC SURVEY OF OHIO. 



The Ohio Legislature has just passed its ap- 

 propriation bill for the year 1901. It contains 

 an item of S25,000 for the inauguration of a to- 

 pographic survey of the State, in co-operation 

 with the United States Geological Survey. 

 This insures the systematic beginning of the 

 field work next year, and the friends of the 

 measure are confident that it will be continued 

 until the entire State is covered. 



The initiative in the movement for securing 

 co-operation was taken by the Ohio State Acad- 

 emy of Sciences at its annual meeting in De- 

 cember, 1S96, since which time a committee of 

 this body has been active in promoting the 

 measure. At the legislative session of 1898 a 

 bill passed the Senate and was in good favor iu 

 the House, largely through the earnest support 

 given it by State Senator James R. Garfield. 

 But the outbreak of the Spanish war necessi- 

 tated a large appropriation for possible military 

 expenditures, and so it was cut oflf. All parties 

 gave the measure increased support in the cam- 

 paign just closed. The scientific societies of 

 the State, including the civil engineers and the 



