Matter and History

Abstract

On 20 May 1663, Francis Glisson brought to the Royal Society a specimen of lignum fossile, “which was given to Mr. Hooke to have it cut even in order to see whether it would polish.” When Hooke showed some thin polished slights of the specimen, Glisson noted that “the petrification of wood was occasioned by the passing of stony juices into the pores of wood throughout, and by filling them all up, and so coagulating there, without changing anything of the figure of the wood.” Hooke’s microscopic observations of the specimens supported Glisson’s hypothesis. Hooke’s account was first published in Evelyn’s Sylva, and then in his Micrographia. As the title suggests, however, the observation “of petrify’d wood and other petrify’d bodies” was not limited to the analysis of the specimen provided by Glisson. In Micrographia Hooke refined the hypothesis of corpuscular “transmutation,” rejected the notion of “plastick virtue,” and introduced the hypothesis of great transformations of the earth’s surface. But Hooke still maintained that a “history of observations well rang’d, examin’d and digested” was needed in order to “perfectly and surely” know the “true original or production of all those kinds of stones.” He undertook this project soon after. After 1665, Hooke collected descriptions of “figured bodies” of all kinds, and observed several fossils through the microscope. In 1667, he reported to the Royal Society the observation of a sequence of horizontal and perpendicular “cliffs of stone near four miles together.” Close to “a cliff in the isle of White” he found “shells of several sorts.” In Hooke’s view, only “some great earthquakes” could have produced those phenomena. The first of Hooke’s Lectures and Discourses of Earthquakes, written on September 15, 1668, includes five tables of illustrations “design’d by Dr. Hooke himself,” as Richard Waller noted. The “strictest survey” and diligent examination of “many hundreds of these figured bodies,” along with the study of the “circumstances obvious enough about them,” led Hooke to propose a consistent hypothesis on the nature of fossils and earth’s history. In the lecture, Hooke reported detailed descriptions of the microscopic observation of many fossils. Although they “resemble” animals and vegetable bodies, “in all other proprieties of their substance, save their shape, are perfect stones, clays, or other earths, and seem to have nothing at all of figure in the inward parts of them.” Such fossils are found below the surface of the earth and in places where the corresponding living species are not present. They are often “inclosed in some of the hardest rocks and thoughest metals.” Through the comparative analysis of these “circumstances” about the “figured bodies” and their microscopic composition Hooke concluded that these are either remains of living organisms “converted into stones by having their pores fill’d up with some petrifying liquid substance,” or the result of “impressions” made on these remains by fluid substances afterwards solidified. Hooke was aware of both the difficulties and the consequences of his conclusions. The corpuscular transmutations of organic bodies into stones are not ordinary processes, since “every kind of matter is not of it self apt to coagulate into a strong substance.” These phenomena are “extraordinary” and mainly due to some “concurrent causes” originating from earthquakes and subterranean eruptions. Earthquakes raised “the superficial parts of the earth above their former level,” created islands and mountains, but also “depressions and sinking of some part of the surface of the earth” leading to “vast vorages and abysses.” During these transformations, “subversions, conversions, and transportations of the parts of the earth” originated the processes of “petrifaction” that transformed organic remains into mineral bodies. Hooke’s hypothesis on the organic origin of fossils clearly entailed significant geo-morphological transformations.