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are too indistinct to be reproduced satisfactorily


Fig. 2
ex R(obert). W. Wood (1868-1955 *), “On the Cause of Dark Lightning and the Clayden Effect.” Nature 61 (November 30, 1899) : 104-105
University of Virgina copy, digitized July 22, 2009 (cropped, from screen shot)

“Fig. 2 is from a plate showing this effect. The upper images are those of single discharges through the capillary, with different apertures of the lens; the lower images are those of double or triple discharges through the same tube. The left-hand side of the plate was exposed to the candle light for different amounts of time, by moving the screen over small distances during the exposure. Only the single discharges reverse, though the density of the images on the unfogged portion of the plate is the same. ¶ This is very strong evidence that the duration of the illumination was the important factor...”

“It seems, then, that we are justified in assuming that the action of an intense light on a plate for a very brief time-interval decreases the sensitiveness of the plate to light...”

epigram from editor’s note re: a Fig. 3, which is not shown.

“A pioneer should have imagination, should be able to enjoy the idea of things more than the things themselves.”

Willa Cather, O Pioneers! (1913)

10 November 2013

Willa Cather; R. W. Wood, “On the Cause of Dark Lightning and the Clayden Effect” (1899)