The term verse denotes poetry written to a certain measure, whether of accents, syllables, time, or another value. Much poetry in the English tradition is metrical, and one of the dominant metrical systems is the so-called accentual syllabic one, whereby lines are measured by groups of accented and unaccented syllables. A line might be predominantly iambic if it can be divided into groupings of two syllables each, with the first syllable in each grouping unaccented and the second one accented. For example, the word beHOLD constitutes an iambic foot, with accent on the second syllable. Thus, five iambic feet in succession produce a line of iambic pentameter—arguably the dominant foot of English metrical poetry.

Many of the terms for describing the metre of English poetry are derived from Latin and Greek metrics. Like English verse, classical verse takes the syllable as a basic unit of measurement as well, but it is not the grouping of accents that determines a line’s metre. Rather, it is the duration of the vowel sounds. Instead of ‘accented’ and ‘unaccented’ syllables, one counts ‘long’ or ‘short’ syllables (so designated by the length of their vowels). Their combinations constitute poetic feet. The three-syllable Latin word ūngŭlă (meaning ‘hoof’) has a long vowel in the first position, followed by two short vowels. The word is thus a dactyl. The most famous dactylic line in classical poetry was the dactylic hexameter: a line comprising six feet, some (but not all) of them dactyls.

John Clark determined that all lines produced by the Eureka would be dactylic hexameters. The measure of the Iliad and Odyssey, this six-foot line is unusually long, compared with the five-foot pentameter and four-foot tetrameter more commonly encountered in the English poetic tradition. The hexameter’s length is exaggerated by the variety of feet that comprise it. Unlike the other two verse lines mentioned, which typically feature two-syllable feet (iambs or trochees), lines of dactylic hexameter can accommodate three-syllable feet (e.g., the dactyl from which the line derives its name, or molossus, a line of three long vowels), though it often contains many ‘long’ two-syllable feet such as the spondee. Notably, the dactylic hexameter is distinctive in being able to accommodate a wide variety of feet, with particular feet being deemed substitutable for others in certain positions. For instance, because two short syllables were typically understood to equal in duration one long one, a spondee might be substituted for a dactyl, or vice versa. The ‘mixed’ nature of the hexameter line is one of its characteristic features—though interestingly it is a feature of the verse that Clark’s Eureka does not allow.

The year 1845, when John Clark exhibited the Eureka at the Egyptian Hall, was a turbulent decade for the hexameter. In 1844 Lancelot Shadwell’s translation of the Iliad into English hexameters had sparked a controversy regarding the possibility of reproducing classical metrical properties in English. This debate was thickened by the publication of experimental English hexameters, such as the American poet Henry Wadsworth Longfellow’s Evangeline (1847) and two narrative poems by Arthur Hugh Clough: The Bothie of Toper-Na-Fuosich (1848) and Amours de Voyage (1849). In 1850 Walter Savage Landor came out against English hexameters in his (hexameter) poem of that title, singing the praises of a putatively more home-grown meter, the pentameter: ‘We have a measure / Fashion’d by Milton’s own hand, a fuller, a deeper, a louder’. Also keen to assess the hexameter’s suitability as a ‘national’ measure, Charles Kingsley not only assayed the meter in 1858 with the publication of Andromeda and Other Poems but also inserted a fictionalized debate on the subject of English hexameters in Westward Ho!, his 1855 historical romance.

In the 1860s these contributions to what was by then clearly a mounting ‘hexameter controversy’ would be complemented by Alfred Tennyson’s ‘On Translations of Homer. Hexameters and Pentameters’ (1863) and Algernon Charles Swinburne’s ‘Hymn to Proserpine’ (1866). Among the more interesting contributors to that decade’s hexameter debate was Matthew Arnold, who endorsed the hexameter as a measure of modernity. His On Translating Homer (1860-1) initiated a heated exchange with Francis W. Newman, whose 1856 ‘ballad-poetry’ translation of the Iliad Arnold dismissed as not ‘noble enough’. As the literary scholar Yopie Prins has noted, Arnold, in his 1857 lecture ‘The Modern Element in Literature’, had associated modernity in literature with poets’ ‘ability to take the measure of their own time’; the hexameter was not only an apt ‘measure’ of the heroic age of Homer but also a meter ‘that might adequately represent and comprehend the multiplicity of the modern age’, both as a template for modern translations of the classical epics and as a medium of original English compositions. Thus, as Prins writes, the ‘hexameter became Arnold’s measure of, and for, the present time’.

The hexameter’s enduring appeal might be explained, in part, by its capacity for accommodating a variety of feet besides the dactyl that gives the measure its name and the differing modes and moods of address that such a rhythmically versatile line affords. As John Seely Hart would remark in his 1871 A Manual of Composition and Rhetoric, in contrast to the ‘prevailing law of English verse’, which states ‘that the feet in any one line shall all be of one kind’ (e.g., lines of iambic pentameter tend to be all, or at least predominantly, iambic), the dactylic hexameter is characterized as a ‘mixed’ measure, where ‘feet of different kinds are mixed together freely in the same line’. In a standard hexameter line, some, though by no means all, of the six feet may be dactyls. ‘The Dactylic Hexameter consists, as its name imports’, wrote William Ramsay in the 1859 edition of his A Manual of Latin Prosody, ‘of six feet; in the first four places, Dactyls or Spondees may be used at pleasure; the fifth foot is usually a Dactyl, the sixth foot invariably a Spondee’.

Such a mixed meter, with its comparative openness to substitution and amenability to poetic licence, provided ample opportunities to vary the inflection of verses, to formalize compositions in direction of high epic or enliven them with an eminently speakable prosiness. On the other hand, however, as a mixed measure where one foot might be changed without necessarily impacting on the next one in sequence or on the overall metrical constitution of the line, the hexameter ran the risk of being as remote from ‘good’ poetry, where deviations from a metrical template might mitigate against rhythmical monotony, as it was susceptible to an arbitrary, and nonetheless mechanical, combination of feet, particularly when the versifier is less aware of or motivated by an awareness of the rhythmical nuances that such a mixed measure promised. There was a difference, in other words, between capitalizing on the mixed metrical character of the hexameter, combining miscellaneous feet to achieve a balanced and rhetorically dynamic line, and merely mixing its feet at random because such an approach satisfied, however loosely, the most basic of rules of versification associated with the measure. This more or less random approach is often associated with the attempts of schoolboys attempting to ‘manufacture’ hexameters in the Latin exercises by whatever means possible.

The compositional mechanics of ‘dactyls, spondees, trochees’ might represent, as John Clark speculated, so many metrical ‘difficulties’ for a pupil of Latin, but was it really the case, again as Clark suggested, that the same ‘Rules of verse’ would ‘have an opposite effect when applied to a machine’? Clark confidently portrayed the Eureka as a device that managed with comparative ease the complicated metrical grinding of scholastic prosody that baffled and often alienated the schoolboy. Yet while his machine, may have appeared to relieve humans of metrical drudgery by substituting a mechanical versifier that performed more or less the same the hexameter exercises, capitalizing on a mixed measure like the hexameter in a mechanized feat of combinatory skill and prosodical prowess, the Eureka was in fact even more limited in its compositions than the most haphazard of schoolboys. Clark might insist, in his ‘General Description of the Hexameter Machine’, that it is the variety both of feet—’Each foot consists of a certain number of Long and Short Syllables’—and of their combination to form a variety of hexameters—’this variety of measure constitutes the variety of cadence in poetical composition’—that the Eureka automates, but in practice the machine reduced the measure to but one variation on the dactylic hexameter. One particular distribution of quantities across the line’s six feet became a mechanically reproducible pattern, where words of the requisite metrical values could be selected from among the machine’s limited store of Latin vocabulary, enabling it to manufacture lines differing considerably in content but not at all in form—each one conformed to the same invariable, though irregular, metrical structure. By first mixing but then resolutely fixing the machine’s hexameters, Clark achieved an apparently ingenious spectacle of automated prosody. As a meter automaton—a machine that appeared to make decisions about versification using its own discriminating prosodic processes—the Eureka worked not by understanding versification generally or even the discrete metrical properties of the dactylic hexameter in particular but by reducing the prosody of this mixed measure to a pre-determined, fixed, and readily repeatable series of data.