Edward Duke opens his pamphlet by confronting the visitor's first question: can we fix Stonehenge's age? He immediately acknowledges the difficulty, noting that the mystery 'adds not a little to the imposing grandeur of those weather-beaten stones.' Yet he asserts confidence that the monument was standing when Roman legions invaded in 55 BC, and his primary aim is to disprove the post-Roman theory advanced by James Fergusson in Rude Stone Monuments.

Duke's method is forensic: he examines archaeological evidence—pottery fragments, deer remains, an iron arrowhead—and scrutinizes historical sources. He targets Fergusson's reliance on Geoffrey of Monmouth, whom Fergusson himself called 'a fabulist of the most exuberant imagination' and 'a frail reed to rely upon.' Duke finds it 'strange' that Fergusson builds his case on such uncorroborated testimony.

A Clash of Inferences

Duke distinguishes sharply between factual observation and the drawing of conclusions. He praises Fergusson for collecting facts 'with care,' but insists that 'the observing faculty and the faculty for drawing correct conclusions do not always meet in the same individual.' To illustrate, he invokes Charles Darwin's physical evolution theory—a pointed comparison that frames Fergusson's error as a failure of inference, not evidence.

The core of Duke's argument is that Fergusson misinterprets archaeological data. When Sir R. C. Hoare reported finding Roman pottery within Stonehenge's circle, Fergusson took this as proof of Roman-era use. Duke counters by citing the late Mr. W. Cunnington, who found similar fragments but believed they 'had found their way into the ground afterwards, from some cause or other.' Duke presents a letter from Cunnington dated October 2, 1801, to support this interpretation.

This section reveals Duke's own method: he privileges the testimony of field archaeologists over armchair theorists. The pamphlet becomes a case study in how the same physical evidence can support opposing chronologies.

The Weight of a Single Witness

Duke devotes considerable space to dismantling Fergusson's reliance on Geoffrey of Monmouth, the 12th-century historian who claimed Stonehenge was erected to commemorate British chiefs slain by Hengist. Duke notes that Fergusson himself admits Geoffrey was 'a fabulist of the most exuberant imagination,' yet builds his entire post-Roman dating on Geoffrey's account. Duke finds this contradiction 'strange' and 'weak and inconclusive.'

The pamphlet's tone here is measured but pointed. Duke does not dismiss Geoffrey entirely; instead, he highlights the logical flaw in using an unreliable source to support a specific historical event. He implies that Fergusson's theory requires more than a single medieval chronicler—it needs corroborating archaeological or documentary evidence, which Duke argues is lacking.

This focus on source criticism gives the pamphlet a surprisingly modern feel. Duke treats Geoffrey as a text to be weighed, not a repository of facts, and he expects his readers to follow the chain of reasoning.

Pottery, Bones, and the Fallen Trilithon

Duke's most concrete evidence comes from excavations within Stonehenge itself. He reports that Sir R. C. Hoare found 'several fragments of Roman as well as coarse British pottery, part of the head and horns of deer and other animals, and a large barbed arrow-head of iron.' For Fergusson, these Roman sherds indicated a post-Roman construction date. Duke counters by citing Mr. Cunnington's view that the pottery was intrusive, having slipped into the ground after the stones fell.

The key piece of evidence is the fall of the great Trilithon in 1797. Cunnington examined the cavity and concluded that the Roman fragments were not original deposits. Duke reproduces a letter from Cunnington to bolster this claim, emphasizing that the excavator himself did not consider the pottery 'proof of the age of the structure.'

Duke thus turns Fergusson's own archaeological evidence against him. The pamphlet argues that context matters: where pottery is found—whether in primary or secondary deposits—determines its value as a chronological marker. This attention to stratigraphy, though rudimentary, shows Duke engaging with the material record on its own terms.

Duke's pamphlet is a concise exercise in historical skepticism. He does not claim to know Stonehenge's precise age, only that it predates the Roman invasion. His method—weighing archaeological context against historical testimony—offers a model for evaluating competing theories. Readers should note that Duke writes as a clergyman and geologist, blending scientific observation with a clear polemical purpose. The pamphlet's brevity (threepence, third edition) belies its careful argumentation.