Considerable attention has been given to the use of more than one geophone on each recording channel with the hope of increasing the signal-to-noise ratio, where 'signal' is taken to mean 'recorded reflection' and 'noise' means any undesired recorded amplitude. The average expectancy of this gain is evaluated analytically, and the statistical distribution examined. Since at different instants this gain possesses different values dependent on a large number of causes, these causes are assumed to be random in nature; a justification of this and other assumptions is explained, and the distribution of gain in terms of frequency of occurrence is expressed in the form of a probability curve. From this analysis an answer can be inferred to the question, 'if n is the number of geophones, what is the probability that a gain of k. n will occur?' The average expectancy of this gain is shown to beEquationThis leads to the conclusion that a large number of geophones per channel is necessary to obtain consistently worthwhile values of gain in signal-to-noise ratio.Aspects incident to application are discussed, and sources of noise which are not random are mentioned.