Joseph Scaliger’s butterfly-locked letter to Francisco Donzà, Europe (c.1593–1606)

Modelled after Bodleian Library, Ms. Bywater 63, f. 52. When Dutch historian Joseph Scaliger (1540–1609) or his letterlocker secured his letter packet shut with a “butterfly lock”, he built security into it which required the recipient to tear the lock…

Joseph Scaliger's butterfly-locked letter to Francisco Donzà, Europe (c.1593–1606)



Modelled after Bodleian Library, Ms. Bywater 63, f. 52.

When Dutch historian Joseph Scaliger (1540–1609) or his letterlocker secured his letter packet shut with a “butterfly lock”, he built security into it which required the recipient to tear the lock at five points to open the letter. Dripping sealing wax over portions of the paper lock not only enabled him to impress his signet but to perfectly preserve the artifact of a high-level snoop deterrent.

To create this sophisticated device, a flat and narrow lock was slit out of the paper, a portion of it remains attached to the folded letter packet as it metamorphoses into a textured and tightly-laced lock. Opened letters like this one—with a column of slits found in every panel parallel to and millimeters from the long edges of the substrate—were secured shut via “recursive perforation”, by which the paper lock is laced through itself and the letter packet using three or more slits.

Before he began writing his letter to Francisco Donzà, Scaliger folded a margin to align his text. Afterwards, the lock was slit out of the blank margin. The letter was folded top to bottom three times, then folded in half short-edge to short-edge. The lock was left free and extended past the folded paper.

Scaliger or his letterlocker (e.g. secretary) then built the butterfly lock. To begin, he made the first of four small slits (3–4mm each) through the packet near the bottom edge. The wider portion of lock, attached to the packet, wrapped around the top two free edges of the packet, folded in half, and laced through the first slit. The next slit was made toward the top edge on the opposite outer panel. As the lock passed through this slit, it also passed through itself for the first time. Each time the loose end of the lock traveled through the slit, it was folded in half, and each time the lock emerged, it was flattened before the next slit was made. The lock was stitched through itself and the packet two more times. The tail of the lock was just long enough to pass through the fourth and final slit made in the middle of the column of slits. The tip of the lock presumably is preserved underneath the sealing wax.

It would be difficult to break into the letter and attempt to match the lock’s built-in anti-tamper attributes: the unique sheet of handmade paper (the interceptor would have to replace the lock, matching perfectly color, texture, thickness, laid and chain line patterns, fiber dispersion in the sheet not to mention attaching a new lock to the sheet of paper and then lacing it through the slits). It would be challenging to remove the sealing wax intact (which embeds into the paper fibers and down into the slits), then unlace the mutilated lock while making sure that the portion of it remains attached to the paper and while not damaging the perforated edges of the paper—so that all could be reused to recreate the pristine-looking tightly-laced lock.

Produced by MIT Video Productions (MVP). Researched, reverse-engineered, directed, and demonstrated by Jana Dambrogio, Thomas F. Peterson (1957) Conservator, Massachusetts Institute of Technology (MIT) Libraries and general editor of and Dictionary of Letterlocking (DoLL).

Funded by the Gladys Krieble Delmas Foundation and the MIT Libraries. Special thanks to Bodleian Library staff: Andrew Honey, Book Conservator; Mike Webb, Curator of Early Modern Archives & Manuscripts; Dr Michelle Chew, Administrative Assistant and Alexandra Franklin, Coordinator, Center for the Book, the reading room staff, Weston Library; and Dr Chris Fletcher, Keeper of Special Collections; MIT Libraries staff: Ayako Letizia, Conservation Associate; Annie Dunn, former student; Emily Hishta Cohen, Intern and Graduate Student, IFA, NYU; and Barry and Ramon, MVP staff; Mary Uthuppuru and Brien Beidler; associate editors of and DoLL; Sarah Manguso; and Dr Daniel Starza Smith Lecturer in Early Modern English Literature (1500–1700), Department of English, King’s College London, UK, and general editor of andDoLL.


Cite as: Jana Dambrogio, et al. ‘Joseph Scaliger’s butterfly locked letter to Francisco Donzà, Europe (c.1593–1606)’, Letterlocking Instructional Videos. Filmed: 09/2016. Duration: 6:08. Posted: 10/2016. Video URL: [Use URL below]. Date accessed: [Date].

Copyright 2016. Jana Dambrogio, Daniel Starza Smith and Massachusetts Institute of Technology (M.I.T). All rights reserved. The following copyrighted material is made available under the Creative Commons Attribution-NonCommercial 4.0 International (CC BY-NC 4.0) License Contact the M.I.T. Technology Licensing Office for any other licensing inquiries.

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