[A very similar lightning flash was described and pictured in the issue of the Electrical World and Engineer for October 28, 1899, by A. E. Kennelly, who suggested the following explanation: A lightning flash passed through the air on the left-hand side of the ribbon of lightning (the wind was blowing from right to left) and broke a hole in the air along that line. This discharge may have been oscillatory, and may have lasted in all any time up to about 1/100 of a second. The discharge then ceased for lack of electricity, but a fresh charge from the cloud being gathered immediately afterward, or in about 1/30 of a second from the first rupture, a new discharge passed through the same hole in the air, which had not had time to seal up. There might thus be fourteen successive flashes (this was the number of distinct flashes making up the ribbon in the photograph), each averaging about 1/25 of a second apart, through the same hole, owing to the imperfect conducting qualities of the clouds overhead, meanwhile the hole having been carried from left to right in the picture, across the line of sight (by the wind), and thus producing the appearance of a broad ribbonlike flash. Professor Trowbridge, of Cambridge, has suggested the possibility that many of these apparently curious electrical phenomena may be of purely optical or physiological origin--that is, may arise through the abnormal behavior of the eye or the camera lens toward intense lines of light, such as lightning flashes.--ED.] CROSS-EDUCATION. BY E. W. SCRIPTURE, DIRECTOR OF THE PSYCHOLOGICAL LABORATORY, YALE UNIVERSITY. Some years ago I made the following simple experiment: I arranged a rubber bulb, like that used for releasing a photographer's shutter, to connect with a bottle, from which rose a long, vertical glass tube. The bottle contained mercury, and the long tube reached nearly to the bottom. Every part was air-tight, so that when anybody squeezed the bulb the mercury was forced up the vertical tube. It was what is known as a mercury-dynamometer. During experiments with this dynamometer, what was more natural than to think of trying what would happen if one hand were practiced daily in squeezing the bulb? So one of our graduate students, Miss E. M. Brown, was set to work in the following manner: On the first day she squeezed the bulb as hard as possible with the left hand, while an assistant noted the height of the mercury; this was repeated ten times, and the results were averaged. Immediately thereafter she took ten records with the right hand. Then, on the following days, with some intermissions, she practiced the right hand by squeezing ten times on each occasion. On the last day she again tested the left hand, which had not been practiced in the meantime. The records ran as follows: