The numerical calculations may be made in such a manner as to make clear the influence of various factors on the results. This is done for the buried source and receiver in a semi-infinite elastic medium. The process is to alter the path of integration so that with increasing time one increases the integration path length. Thus the total field unfolds as we carry out the integration.

The work is done graphically. The path is mapped by an electrolytic tank technique suitably modified from that used by electric network synthesis workers. The integrand is separated into a product of two terms, one independent of time and position and one dependent on time and position. The independent term can be mapped on a conducting sheet for one Poisson ratio. The dependent term may be mapped for each time and position.

A function multiplier and integrator are needed. The method is most accurate when the horizontal distance of the receiver is not very large compared with the sum of the depths of the source and receiver. The method is alterable to include the domain of difficult direct application.

Every aspect of the methods herein described may be extended in the practical sense to the more general case treated by Cagniard. This is, in fact, the main justification for this study of an old problem.

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