. Early geophysical papers of the Society of Exploration Geophysicists. Petroleum; Prospecting. VELOCITY OF ELASTIC WAVES IN GRANITE 59 The distance travelled by the waves and the time required constituted the observed data. Distances were scaled from the maps reproduced in Fig. 1. The time plotted against the distance yielded a time-distance graph which was a straight line through the origin. The velocity, the reciprocal slope of this line, was computed by a least square solution. •'fc / 67 ^V. t S3. \ V, A. o 76£) / \ .58 1 \ »7*. j 60 14 / 62/ 69 \ 108' V \ \" ^=5^ ^H- *£** » V1 70£^43
. Early geophysical papers of the Society of Exploration Geophysicists. Petroleum; Prospecting. VELOCITY OF ELASTIC WAVES IN GRANITE 59 The distance travelled by the waves and the time required constituted the observed data. Distances were scaled from the maps reproduced in Fig. 1. The time plotted against the distance yielded a time-distance graph which was a straight line through the origin. The velocity, the reciprocal slope of this line, was computed by a least square solution. •'fc / 67 ^V. t S3. \ V, A. o 76£) / \ .58 1 \ »7*. j 60 14 / 62/ 69 \ 108' V \ \" ^=5^ ^H- *£** » V1 70£^43 \ 72 73 \ SHOT & RECORDING LOCATIONS OF THE QUINCY AREA loo tt 38 f •45. Fig. 1. III. Instruments The seismograph used at Quincy consisted of three components, two horizontal and one vertical, mounted on a single base. The instrument was always oriented so that one of the horizontal components recorded vibrations on a line from shot to recorder, while the other, at right angles to this, recorded vibrations transverse to that line. These are designated respectively as the longitudinal and transverse components. The longitudinal component had a free period of sec, the transverse, of sec, and the vertical, of sec Each was critically damped by a magnetic device of conventional design. The static magnification, effected by mechanical and optical means, was about one thousand. At Westerly and Rockport, a vertical component seismograph was used. It had a free period of approximately two tenths of a second and was criti- cally damped by a piston working in a cup of oil. The static magnification, also mechanical and optical, was about twelve thousand. Both of the instruments recorded photographically on a strip of bromide paper one inch wide, moving at a speed of about twenty centimeters per 203. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illu
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Keywords: ., bo, bookcentury1900, booksubjectpetroleum, booksubjectprospecting
