Richard de Grijs
Sydney, Australia

In the dim confines of a ship’s sickbay during the golden age of piracy, the sound of waves might have been interrupted by the rasp and twist of a surgical drill biting into bone. Trepanning—the act of boring into the skull to relieve the pressure on the brain following head trauma—was one of the most dramatic interventions in the sea surgeon’s repertoire. It was known as a “capital” operation given its considerable mortality. Trepanning was a practice born of necessity, rooted in antiquity, but refined by the perils of naval warfare and maritime life.

By the late seventeenth century, trepanning was both feared and celebrated, an art with ancient lineage and contemporary innovation. The tools used—principally the trepan and trephine—embodied centuries of practical refinement and surgical philosophy. Yet at sea, far from the hospitals and academic theaters of Europe, they took on a rawer, more improvisational quality, shaped as much by shipboard conditions as by theoretical knowledge.

Samuel Johnson’s (1709–1784) dictionary (1768) defined a trepan as “an instrument by which chirurgeons cut out [a] round piece of the skull;” a trephine was “a small trepan … managed by one hand.”¹ His definitions reflect the evolving distinction between two functionally similar tools. The trepan, older in origin, resembled a carpenter’s brace—turned with two hands, often heavy, for cutting with speed and force. The trephine, however, was lighter and more agile, designed with a T-shaped handle for one-handed control.²

The distinction was not merely semantic. The trepan, into the early modern period sometimes still fashioned like a brace drill, enabled rapid cutting—an advantage in the chaos of battle or rough weather. Trephines, first described by sea surgeon John Woodall (1570–1643), offered practitioners greater finesse.³ Woodall, whose Surgeon’s Mate (1617, expanded 1639) was the “bible” of naval medicine, claimed that his new trefine—after the Latin tres fines, “three ends”—provided not just cutting ability but also acted as its own elevator, a tool used to lift skin, brain tissue, bone fragments, or to assist in manipulating the blade.⁴

The choice of a trepan or a trephine became a point of contention among surgeons. Richard Wiseman (1620?–1676), former Sergeant-Surgeon to King Charles II, staunchly defended the trepan in his Severall Chirurgicall Treatises (1676), arguing that it cut more evenly and with less force on the cranium than the trephine. “It doth its work lightly, and cutteth Bone equally,” he wrote, even noting that patients’ families, invited to trial the instruments on a skull, unanimously preferred it.⁵

Woodall disagreed. His T-handled trefine, he argued, could “perform as much as the Trapan in every degree and more”—it allowed the surgeon to control pressure with greater subtlety.⁶ His preferred design also featured a crucial innovation: tapered blades, which widened toward the top and thus restricted over-penetration. This reduced the risk of damaging the dura mater—the tough membrane between skull and brain—a real danger in the age of blind operations.⁷

Blades of precision and peril

Whatever the handle, the trepanning instrument was defined by its blade. At least five types were used by early modern surgeons, each with its own purpose and limitations⁸:

1. The piercer blade was a preparatory instrument. Shaped like a spike, it bored a shallow hole to seat the center pin of a larger cutting blade.⁹ Without it, the more aggressive circular blades could slip, gouging bone unpredictably.
2. More controversial was the exfoliative blade, a flat-edged tool used to scrape rather than cut, lifting successive thin layers of skull. Ambroise Paré (1510–1590), the renowned French royal barber-surgeon, approved its use for superficial fractures.¹⁰ His compatriot Pierre Dionis (1643–1718), however, dismissed it with disdain: “That way of piercing the Bone by scraping it … must very much shock the Head, and do more Mischief than Good.”¹¹
3. The knife crown blade, mostly by French surgeons, allowed cutting through the skin and muscle with a circular incision. Jacques Guillemeau (1550–1613), Paré’s pupil, praised its ability to minimize blood flow, but it seemed to have fallen out of favor in England—possibly because of the surgical wisdom that round wounds heal poorly.¹²
4. More common was the serrated crown blade, containing a circular toothed edge and a central pin for guidance. To prevent this aggressive blade from plunging too deeply once it pierced the outer skull, a cap could be screwed or pinned to the shaft, thus limiting depth.¹³ But even this safety feature proved fallible. If the cap slipped or the screw loosened, the blade could plunge into the brain. Woodall described it as “very apt on the suddaine to slip downe upon the Dura Mater … by error and improvidence of the Artist.”¹⁴
5. To counter this risk, Woodall introduced the tapered blade, the crown of his surgical innovations. Designed to widen upward, it stopped naturally before reaching dangerous depths.¹⁵ John Atkins (1685–1757), an early eighteenth-century naval surgeon, confirmed its practicality, noting that “the Diameter enlarging upwards” protected the brain from injury.¹⁶

Surgery at sea

Trepanning at sea was rarely elective. Shipboard life abounded with opportunities for head trauma: falling spars, splintering timbers, accidental falls, fist fights or other altercations, boarding actions, and the occasional musket ball. Without the modern luxury of diagnostic imaging or laboratory tests, sea surgeons were forced to rely on touch, observation, and a grisly kind of intuition.

John Moyle (d. 1713/4), a prolific author on maritime medicine, advised packing only essential tools, since the surgeon’s two chests—one for drugs, one for instruments—had limited space.¹⁷ Trepanning tools were not always part of these kits and, when present, were likely bundled with general-use items rather than carried in the luxurious, purpose-designed trephination sets routinely encountered in land-based hospitals.¹⁸

Nevertheless, when needed, the trepan or trephine had to be sharp, clean, and ready. Woodall cautioned against dull or rusty tools, warning that an off-center pin could make the blade “run not true,” sawing jaggedly and enlarging wounds unnecessarily.¹⁹ The surgeon also needed a selection of blade sizes: Dionis and Woodall both advised starting small, opening the cranium just enough to relieve pressure, drain an intracranial hematoma, or remove bone shards.²⁰ A large opening, Dionis warned, left the brain dangerously exposed and made the wound harder to heal.²¹

On the cramped, poorly-lit lower decks, the situation would have been even more fraught. A patient might be drunk, delirious, or bleeding profusely; assistants might be inexperienced sailors rather than trained dressers. Yet despite the risks, some sea surgeons became proficient practitioners. Atkins, for instance, described a method of beginning the operation with the trepan to gain speed, then finishing with the more controlled trephine—a tactical blend of efficiency and caution.²² Abraham Titsingh (1684–1776) was clearly aware which locations on the head should not be trephined:

It should also be noted that one should not trephine on the sutures too lightly, and never on the Sutura Sagittalis [interparietal suture], because there the Sinus Longitudinalis runs under it; for if one were to drill into it, one would obtain such a great blood discharge that death must necessarily follow.²³

One frequently overlooked but telling tool in the trepanning kit was the bone dust brush. Usually made with soft bristles or feathers, it was used to sweep bone dust from the teeth of the trepan blade or from the skull itself.²⁴ Although common in the eighteenth century, its maritime use is less well documented. The first mention of the brush in a surgical context comes from Dionis in the early 1700s. He instructed surgeons to “clear [the blade] of the Saw-Dust and Blood with the little Brush … before we fix it on again.”²⁵ Atkins was the only sea surgeon known to reference such a tool, advising use of a “little Feather-Brush” to keep wounds clean.²⁶ Its appearance in surgery is another sign of the evolving attention to detail and hygiene, even if antiseptic theory was still a century away.

Trepanning kits themselves—neatly cased assemblages of crown blades, elevators, lenticulars, and brushes—were prestige collections. Most extant examples date from after 1750, yet it is doubtful whether the average ship’s surgeon could actually afford them.²⁷ Instruments were often provided by the ship, selected for utility rather than elegance. William Fabry’s (1560–1634) Cista Militaris (1674) provided a comprehensive list of necessities for a military or naval chest, emphasizing practicality and flexibility.²⁸

Moyle warned against excess: “You are not to carry greater variety than of necessity you must.”²⁹ On merchant ships in particular, where the surgeon might be hired ad hoc and expected to provide his own equipment, choices had to be economical and portable.³⁰ The tools of cranial surgery—like much of early modern medicine—had to serve many masters in cramped and unpredictable environments.

In the modern imagination, trepanning is often dismissed as crude butchery—an emblem of pre-scientific medicine. But the reality aboard ships during the golden age of piracy was more nuanced. Far from mindless drilling, trepanning demanded mechanical skill, anatomical knowledge, and nerve.

Whether wielding a brace-handled trepan in the chaos of battle or a T-bar-type trephine in the quiet desperation of the sickbay, the sea surgeon’s task was the same: to give the brain room to breathe, to lift a splintered shard, or to relieve the fatal pressure of a closed head wound. The tools they used—simple, dangerous, elegant—are silent testimony to their craft, and to the fine line between healing and harm in an age where even a breath of relief came at the edge of steel.

References

1. Johnson, S, A Dictionary of the English Language, 3^rd ed. (Dublin: W.G. Jones, 1768).
2. Ibid.
3. Keynes, G, “John Woodall, Surgeon, His Place in Medical History,” J. Roy. Coll. Physicians Lond., 2(1), 15–33 (1967).
4. Woodall, J, The Surgion’s Mate or Military and Domestique Surgery (London: Rob. Young, 1639), 313.
5. Wiseman, R, Severall Chirurgicall Treatises (London: E. Flesher and J. Macock, 1676), 393–397.
6. Woodall, The Surgion’s Mate, 313.
7. Ibid., 314.
8. Kehoe, M, “Head Surgery Tools from the Golden Age of Piracy,” The Pirate Surgeon’s Journals. Tools and Procedures (2003–2025), 6. https://www.piratesurgeon.com/pages/surgeon_pages/head_tools6.html. Accessed July 11, 2025.
9. Dionis, P, A Course of Chirurgical Operations Demonstrated in the Royal Garden at Paris, translated (London: Printed for J. Tonson, 1733), 283–284.
10. Paré, A, The Workes (London: Richard Cotes and Willi Du-gard, 1649), 269.
11. Dionis, A Course of Chirurgical Operations, 279–280.
12. Guillemeau, J, The French Chirurgerie (Dort: Isaac Canin, 1597), unpaginated.
13. Ibid.
14. Woodall, The Surgion’s Mate, 314.
15. Ibid.
16. Atkins, J, The Navy Surgeon (London: J. Hodges, 1742), 86–87.
17. Moyle, J, Abstractum Chirurgæ Marinæ (London: J. Richardson, 1686), 4.
18. Arbittier, D, Neurosurgical Antiques, medicalantiques.com (1998–2025). Accessed July 8, 2025.
19. Woodall, The Surgion’s Mate, 316.
20. Dionis, A Course of Chirurgical Operations, 280; Woodall, J, The Surgion’s Mate (London: Edward Grippin, 1617), 5.
21. Dionis, A Course of Chirurgical Operations, 283.
22. Atkins, The Navy Surgeon, 86.
23. Banga, JJ, Geschiedenis van de Geneeskunde en van hare beoefenaren in Nederland, II (Leeuwarden: Eekhoff, 1868), 53 (in Dutch).
24. Kirkup, J, The Evolution of Surgical Instruments (Novato, CA: historyofscience.com, 2005), 78.
25. Dionis, A Course of Chirurgical Operations, 284.
26. Atkins, The Navy Surgeon, 87.
27. Arbittier, op. cit.
28. Fabry, W, Cista Militaris (London: W. Godbid, 1674), 9.
29. Moyle, Abstractum Chirurgæ Marinæ, 4.
30. Moyle, J, Chirurgus marinus: or, The Sea Chirurgeon (London: Eben. Tracy and H. Bernard, 1693), 46.