Specific and Non-specific Factors in Psychopharmacology

1881). These provide a wealth of detailed information about Lyell's life, though with frequent and often tantalizing gaps, but they make no attempt to trace the development of his scientific work nor to estimate it critically. They shun controversy absolutely. In 1901 T. G. Bonney of Cambridge University issued a short popular life, Charles Lyell and Modern Geology, which, despite its brevity, did attempt a critical estimate of Lyell. This estimate was difficult to make not only because Bonney was close to Lyell in time, but because Lyell's stature as a geologist appeared to hinge on the resolution of geological disputes at that time still unsettled. Lyell's reputation was closely linked to that of the doctrine of uniformitarianism which he had begun to expound in the first volume of his Principles of Geology in 1830. According to Lyell geological processes had gone on in the past in the same slow and gradual way in which they appear to be going on at the present time. In order therefore to account for the vast geological changes which patently had occurred, Lyell had to postulate a very great age for the earth. However, the age of the earth had been a matter of controversy since 1865 when William Thomson, later Lord Kelvin, attempted to show from the rate of cooling of the earth that its life must be relatively short. In the last ten years of his life Lyell combated Kelvin with geological data, which the latter contemptuously ignored. After Lyell's death the physicists reduced the age of the earth to as low as 10 million years. Although this absurd figure was later increased, Bonney still considered the estimate most widely accepted in his time to be 100 million years-less than 1/30 of the modern estimate. For this reason he felt obliged to concede that Lyell had probably carried the principle of uniformity too far. Geological change therefore must have been swifter and periodically it must have been catastrophic. The discovery of radioactivity as a source of heat within the earth, however, destroyed the basis of Kelvin's calculations and, by vastly extending the history of the earth, has vindicated Lyell. This significance of Lyell to geological theory is not dwelt upon by Sir Edward Bailey. He has given more attention to Lyell's numerous contributions to particular aspects of geology and is able to give Lyell a high score as a geological observer and interpreter. He does not, however, make clear why Charles Darwin should have said: "The science of geology is enormously indebted to Lyell-more so, as I believe, than to any other man who ever lived." LEONARD G. WILSON