Page:Popular Science Monthly Volume 30.djvu/136

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THE POPULAR SCIENCE MONTHLY.

most severe and was the ono that did the principal damage. The second shock lasted four seconds, and the third and fourth shocks were very light. Professor Newcomb observed three shocks, the first of which he fixed at 9.53.20. Mr.McGee, after the culmination of the first shock, timed the phenomena, improvising a seismoscope out of a tumbler of water placed on a stand, and a rude seismometer out of the high head-board of his bedstead. The following is the record of his observations:

"Time of culmination of first shock (seventy-fifth meridian) 9.5412; duration of first shock (estimated), eighty seconds; time of termination of same, 9.55; time of termination of the slight tremor, 10.00 (several slight tremors followed but were not timed); time of recommencement of continuous tremors, 10.08; time of culmination of the second shock, 10.0912; duration of second shock, about thirty seconds; time of termination of second series of tremors, 10.13. The direction of vibration, as indicated by the improvised seismoscope, was a little north of east, but there was an indeterminate vertical component in the undulation plainly perceptible in the motions of liquids and of articles of furniture. Roughly, the upward impulse in each vibration appeared to be one third or one half of the lateral impulse.

"The rate of vibration was measured on the high, swinging head-board of a bedstead during the second shock, and found to be one hundred and fifteen or one hundred, and twenty per minute. During the second shock the head-board, eight and a half feet high, swung through an arc of from one half to three quarters of an inch. It was estimated that the amplitude of oscillation during the earlier shock was twice or thrice as great."

Mr.Richard Randolph, civil engineer, of Baltimore, gives the time of the first shock as 9.5312. The oscillations in his room were emphasized by the synchronous beating of some object in his bedroom, which upon examination he found to be the tapping of the door of a wardrobe, and that, he observes, could only be produced with an east-and-west oscillation. To reproduce the tappings with the intensity and period that marked them during the earth-movement required a movement of half an inch at six and a half feet from the floor, for a complete oscillation. At Rochester, New York, a magnetic storm was observed to be raging all the morning of September 1st. It was observed, at the Signal-Service Office in Washington, that the self-registering wind-vane showed a horizontal mark preceding and subsequent to the shaking, denoting a mild, steady breeze, but, for the thirty or forty seconds of most violent shaking, the marks indicated great and rapid agitations of the registering-pencil. Captain Vogel, of the steamer city of Palatka, observed at sea, twelve miles off Port Royal, "a terrible rumbling sensation," which lasted about a minute and a half. There had been a heavy sea from the southeast, but when the rumbling began the wave-motion ceased and the waters remained perfectly quiet until the rumbling stopped, when the wave-motion again became manifest. The depth of the water at Charleston has not been greatly affected; but, according to Captain Boutelle, it has been increased by from six inches to a foot. Fainter shocks have been reported from Charleston as occurring nearly every day since the principal catastrophe.


THE BRITISH AND FRENCH ASSOCIATIONS.

The meetings of the British and French Associations this year were successful from both scientific and material points of view. The city of Birmingham, where the British Association met, provided so well for the accommodation and entertainment of its guests, that Mr.Galton, in seconding the usual