At a glanceCiphertext-only break · partial (90% of the cipher)
- The letter
- A letter of Antonio Ferdinando Gonzaga, Duke of Guastalla, dated “Guastalla 24 7bre 1717” (September; the catalogue says July), to a correspondent not named: clear opening and closing, cipher between.
- Where
- Biblioteca Estense Universitaria, Modena, Autografoteca Campori, Lettera A, “Antonio Ferdinando, duca di Guastalla”, cc. 15–16; ledger entry 1569, which listed it with two other Campori letters in other ciphers.
- The cipher
- Two-digit numbers for letters in alphabet order from a = 30 to z = 67, a single last digit for a final vowel, and a few code numbers for words and names.
- How it was deciphered
- Prabal Gupta reports that he found the key from this letter alone by count matching on Italian letter counts. Checked here: the key decrypts the letter into Italian and a sequence match against his decryption gives 95.2%; a word-list control against 300 shuffled keys is weak, and the scans were not seen.
- What it says
- The duke cannot answer until he is told whether the claim of a “lettera reversale” has been dropped, which he calls “una tacita abdicazione delle mie ragioni”; he will take the land only in the form of the old investitures.
- Still open
- Ten code groups, a few doubtful passages, no comparison with the scans, and the recipient’s papers and the Vienna archives not searched.
- Credit
- The key, the transcription and the reading are Prabal Gupta’s (issue #329; repository, CC BY 4.0). The scans were not seen here and are not reproduced.
01 The letter
Four pages in the Autografoteca Campori of the Biblioteca Estense in Modena (Lettera A, “Antonio Ferdinando, duca di Guastalla”, cc. 15–16), in Italian: a clear opening and closing, and a cipher of numbers between them. The signature is “Ant. Ferd. Gonzaga”, Antonio Ferdinando Gonzaga, Duke of Guastalla; the correspondent is not named. The Estense record calls it “Lettera parzialmente cifrata”, mentions no decipherment and dates it 24 July 1717. The dateline of the letter reads “Guastalla 24 7bre 1717”, and in letters of the time “7bre” means September, so the date here is 24 September 1717.
The ledger listed the letter with two other Campori letters (Augustoni, 1612; Olivazzi, 1725) in one entry; they use other ciphers and stay there. The contributor, Prabal Gupta, read the letter from the scans; the project could not reach them (the Estense images are licensed CC BY-NC-SA) and worked from his files.
02 The key and its test
Letters are two-digit numbers in alphabet order from a = 30 to z = 67 (b = 25 is an exception). Some letters have a twin (e is 37, 77 or 38; a is 30, 70 or 54), and the writer’s 3 and 7 in the first digit are hard to tell apart, so the transcription writes 3. A word may end in one single digit for its last vowel: 5 a, 6 e, 7 i, 8 o, 9 u. A few short numbers stand for whole words (2 che, 18 non, 1 e, from context), and about ten other code groups, probably names and titles, stay unread: 10, 11, 12, 13, 14, 16, 20, 26, 92 and 93.
The contributor reports that he found the key from this letter alone, with no other letter, key or crib, by count matching and a fit on Italian letter counts. His own tests, which the project did not repeat: a key found from the first half alone agrees with the full key on 98.3% of the second half; a blind reader called the text Italian and translated about 85% of the sense.
Checked here, with an own script: decrypting the cipher groups again with key.tsv gives 1,668 letters; a sequence match against the contributor’s decryption (1,600 letters) gives 95.2%. A word-list test, about 130 common Italian words against 300 shuffled versions of the two-digit key, gives 35.2% of the letters in listed words for the key, a mean of 17.7% and a best of 34.5% for the shuffles. That separates the key from the average shuffle but not clearly from the best one, so it is a weak control. The project relies instead on the decryption reading as Italian sentences.
03 The reading
The cipher part is built into 23 clauses (reading.md, with an English translation). It opens, in the contributor’s reading: in sostanza vedo [che] era ritornato da’ suoi beni il […] Trauston [?Trautson] (“in substance I see that Trautson had come back from his estates”); Starhemberg and Trautson were expected the following week. The duke cannot answer until he is told whether the claim of a “lettera reversale” has been dropped: that letter has the same effect as the eleventh article of the declaration, and worse, “una tacita abdicazione delle mie ragioni, alla quale non sarò mai per aderire” (“a tacit abdication of my rights, to which I will never agree”). He will accept the land only in the form of the old investitures usually granted to his forebears, with no harm to himself or his heirs; the income of the territory is too small to justify any loss of rights; whatever he does will be out of regard for the high merit of a person written in code groups 92 and 93, perhaps the Emperor (a guess). The clear closing wishes the correspondent’s son, “il Signor Contino”, a return to health.
Trautson and Starhemberg are the contributor’s reading of names in the cipher; he matches them to ministers of the imperial court in 1717 and has not checked that in print, and neither has the project. He also reports that Ireneo Affò’s history of Guastalla (vol. IV, 1785) tells of talks that led to an imperial draft of January 1718, which fits September; Affò does not quote or decipher this letter.
04 What remains uncertain
- Ten code groups (10, 11, 12, 13, 14, 16, 20, 26, 92, 93) are unread or doubtful. Counting the cipher part of the reading as 356 units, with a code group in brackets counted as one, 34 carry an unread code group or a question mark, so 322 of 356 (90.4%) read.
- Doubtful passages marked [?] in the reading: page 1 line 15, page 3 line 4, page 4 line 9 and a few single words, where the shapes of 3 and 7 or other digits are ambiguous and only the sense chose between readings.
- The scans were not seen by the project, so the transcription (two passes agreeing on 92.0% of 3,064 digits, by the contributor’s count) has not been compared with them (the transcription file itself holds 3,095 digits), and no human has repeated the check.
- The recipient’s papers, the Gonzaga of Guastalla papers in Parma and Mantua and the imperial archives in Vienna were not searched; a draft or clear copy may survive there, and the letter may be known to historians.
- No statistical validation is recorded for the key.
Full texts
The transcription and the decryption of every document on this page, so that the reading can be used and checked. Short files are shown here; all are in the repository.
Letter of the Duke of Guastalla, 24 September 1717 (Estense, Autografoteca Campori, cc. 15-16) read in part
A letter of Antonio Ferdinando Gonzaga, Duke of Guastalla, to a correspondent not named, in the autumn of 1717: in the contributor's reading Trautson is back from his estates and Starhemberg and Trautson are expected the following week (names read in the cipher, not checked in print); the duke cannot answer until he is told whether the claim of a lettera reversale has been dropped, which he calls a tacit abdication of his rights, and he will take the land only in the form of the old investitures; the income is too small to justify a loss of rights; the clear close wishes the correspondent's son a return to health.
Builds coherent sentences, but under the read bar of 95% of words read as sense (90% here); the holes are marked in the reading.
Transcription
# Guastalla, 24 September 1717 (Biblioteca Estense, Autografoteca Campori, Lettera A, cc. 15-16): transcription. # Two passes; each difference was settled on the full-size scan. Where the passes disagreed on a 3 or a 7 # in the first digit of a pair, this text writes 3. Clear text is in << >>. A '?' marks a doubtful digit. p1 L01: <<Ricevo il gradito Lei foglio di 15 cor.te dal quale>> 4346 p1 L02: 635163 643046675 6537368 2 37625 6243 645162 p1 L03: 4630648 365 63 65 517 2537467 43 44 126 116 6462 p1 L04: 306563 645146 12 63 3064 37463637 6530468 445 p1 L05: 636563 374165 3746646 6377? 64 434530465 447 1261? p1 L06: 106 1 118 63643062 3745 25 776241 12 64625 2063 p1 L07: 30636037 643065 30468 446 45436 624363 605163 p1 L08: 646 636544 64374651626 3637446 30466437 3577? p1 L09: 363746647 44377 44 37 64 38626 6335624364 37457 p1 L10: 635160625 3637446 6165 30447 61653046 645146 61 656 p1 L11: 457 646251657 423065 3762446 257063 6477 635144 45 p1 L12: 3746646 624363 605163648 448 63355162638 5162 p1 L13: 3643463062438 18 44306335438 4346 11 363626 p1 L14: 604443 35 3062446 2 18 638 61653044 6243 636051 p1 L15: 63645 60439 606237 3543635 3630626 13 76544377 p1 L16: 354243 3062304537 46 646 18 457 637 3643355 636 p1 L17: 63435 51 18 63 6430645 514577635 445 60623764 p1 L18: 3746 634351466 3637445 44 37 64 37625 6237 653762 p1 L19: 6330446 3551456 12[sup o] 2 395 44 43636437 63436343458 p1 L20: 3739 77 648 363744 7062 6443 3551448 65 46 3637 3543458 p1 L21: 3637445 93[sup o] 7643754243 7062 30674351466 3046 637 p2 L01: 6037414351626 653746 3746368 30363763 77 626 6546 p2 L02: 30648 6051634 3 64 43658 36 7025 3643 35 3067 4351466 p2 L03: 3637446 45436 623041 4351467 3044 6165 30446 18 6370? p2 L04: 628 45307 603762 3036376243626 603762 18 3930626 p2 L05: 30456 130445 454335 3530635 6546 3551637 37654336 p2 L06: 3746646 60623741 4365 3643 67438 [#] 6037628 636430628 p2 L07: 3064 7746363846368 2 44377 457 603062447 3542 p2 L08: 4370628 14346 6437 624543467 605163 43 64 43657 639 p2 L09: 6470446 447764 77625 6237653762 6330446 633746675 p2 L10: 367 2 18 638 2 624363605163645 3630626 1414352 p2 L11: 37445 45 425 63356243648 2 18 637 606237 643746 p2 L12: 366 365456 636 18 12 2 637 6062306443 355 355145 p2 L13: 65463745 3746646 4637446 149 36374144 3044 64 627 p2 L14: 393765367 446 62776044 43358 2 13 44 149 2 634346 p2 L15: 643746 366 3551463537 363762 457 63435 6337355146368 p2 L16: 445 395162455 164374651626 3637446 304664 43 2 6364 p2 L17: 30646 6351 4443 643045 3746646 3551463577 636 30 p2 L18: 4543 377 4530414351627 605163776351627 3637 44 p2 L19: 64776243645162438 2 637 64 6230645 367 35373637 p2 L20: 62457 1 3551637 633746675 4344 454346 43458 606237 p2 L21: 4143 65364367508 45438 13637445 45435 6051636437 p2 L22: 6243645 18 423065628 76433943 355144 645 3036 p2 L23: 30353764 3062445 455 13 657 637 655144376337 628 p3 L01: 306051626 355146364367 4351467 466551656 37445456 p3 L02: 446 306543637 355146 6465645 445 4530414351626 p3 L03: 364363 64 4346 674351466 13 6051635 3930626543 p3 L04: 446 45436 6243394437634335146 7 1 6243633514465 37 p3 L05: 626 12 457 6451624630625 30 355146648 466 63 65 p3 L06: 11[sup o] 4530643762435 63306062377 60439 2 3041435146 p3 L07: 4137626 355146 6537463746365145 2 3064 77463637 626 p3 L08: 365 44377 446 6062373543636 624363605163646 1 p3 L09: 624363514465 67 4351467 639 446 62434437 65 30646 p3 L10: 3046 6437 3637646 3643 39 43 355144 645 423065646 p3 L11: 446 616530447 18 603762 3637628 4551433746 6452 p3 L12: 367 643745608 4637 44 624363605146 3637626 18 445 p3 L13: 633543 3046368 367 605162446 46516530453746646 p3 L14: 4346 355146 6343 3637 62306743514662 4344 6237 p3 L15: 3643648 363744 6437 6243 645162438 3035374630 p3 L16: 6451457 4637445 4651645 45304636306430457 6243 p3 L17: 3763356? 3551637 643746656 1 454363 37 62302543446 p3 L18: 30 35514639 625146648 363744 4346 644337628 105 p3 L19: 648 367 121 2 18 45376243645 45307 2 438 4543 p3 L20: 4430633543 4465634346 4130626 30 3930624543 p3 L21: 4344 454346 43458 606237414365 364367438 6243 p3 L22: 60625164376364 3046 3651457 [x mark]2 61653046648 6330626 p3 L23: 603762 393062 43463530638 18 654346 6437 62653746 p4 L01: 415 606237414365 364367438 3637446 45436 6230 p4 L02: 414351467 6320625 633745 60626 30 355146 643745 p4 L03: 604430674351466 363744 6351458 45376243 648 367 p4 L04: 92 93[mark] 603762 35657 423065628 6337456062 37 445 p4 L05: 60439 516337616543516 35 653746 386230674351466 p4 L06: 355146 63603762304667 5 63435 603762 393062457 p4 L07: 355144 643745608 4151 3637626 4144 30647 3637445 p4 L08: 413746376251634363 43455 63655 4565 4643 3943 p4 L09: 353746675 1 43463551625162415 414365 6364 4367435 p4 L10-L14: <<Intendo con molto spiacere il mal stato di salute del Sr. Contino Lei figlio, comprendendo l'agitazione d'animo che Lei ne prova, e prego il Sig.re ridonare allo stesso la primiera sanità, ed a Lei ogni vero bene. Guastalla 24 [7bre?] 1717>> (clear, read at 1000 px only)
Decryption
# Guastalla, 24 September 1717: decryption of transcription.txt with the key in key.tsv, found from the ciphertext alone.
# One line per manuscript line. The writer's group breaks are kept as spaces; they are not always word breaks.
# Numbers read as codes are shown in braces, for example {2.}.
p1 L01: in
p1 L02: sos tanza uedo {2.} era ri tor
p1 L03: nato da s u oi {25}eni i l {12}e {11}e tr
p1 L04: aus ton {12} s at ende uano la
p1 L05: sus egu ente se t imana li {12}q
p1 L06: {10}e {1.} {11}o star em {25} erg {12} tra {20}s
p1 L07: aspe tau ano le mie ris pos
p1 L08: te sul tenore dele ante ce
p1 L09: denti lei l e t ere scrit emi
p1 L10: sopra dele qu ali quan ton q ue
p1 L11: mi troui hau erle {25}as te sol m
p1 L12: ente ris posto lo scorso or
p1 L13: dinario {18} lascio in {11} dd{26}
p1 L14: pli c arle {2.} {18} so qual ri spo
p1 L15: sta pi{9.} pre cisa dare {13} raie
p1 L16: chi arame n te {18} mi si dica se
p1 L17: sia o {18} s tata omesa la pret
p1 L18: en sione dela l e t era re uer
p1 L19: sale come {12} {2.} fa l iste sisimo
p1 L20: ef e to del ar ti colo u n de cimo
p1 L21: dela {93} richi ar azione an si
p2 L01: pegiore uen endo ades e re un
p2 L02: ato post a t iuo d a{25} di c az ione
p2 L03: dele mie rag ioni al qu ale {18} sa
p2 L04: ro mai per aderire per {18} fare
p2 L05: ame {13}am mic casa un cosi euid
p2 L06: ente preg iu di zio pero staro
p2 L07: at endendo {2.} lei mi parli ch
p2 L08: iaro {14}ue te rmini pos i t iui s{9.}
p2 L09: tale let era reuer sale senza
p2 L10: di {2.} {18} so {2.} risposta dare {14}{14}c{2.}
p2 L11: ela m ha scrito {2.} {18} si pre ten
p2 L12: de dal se {18} {12} {2.} si prati ca com
p2 L13: unem ente nele {14}{9.} degl al t ri
p2 L14: feudi le repl ico {2.} {13} l {14}{9.} {2.} sin
p2 L15: ten de conce der mi sia secondo
p2 L16: la forma {16}iou{16}{26} dele ant i {2.} st
p2 L17: ate so li tam ente conce se a
p2 L18: mi ei magiori posesori de l
p2 L19: teritorio {2.} si t rata di cede
p2 L20: rmi {1.} cosi senza il min imo pre
p2 L21: gi udizio mio {13}som mia poste
p2 L22: rita {18} hauro rifi col ta ad
p2 L23: acet arla ma {13} ui si uolese ro
p3 L01: apore condiz ioni nuoue elal
p3 L02: le auisi con tuta la magiore
p3 L03: dis t in zione {13} posa farui
p3 L04: le mie riflesic{14}e i {1.} risc{14}na e
p3 L05: re {12} mi tornara a conto ne s u
p3 L06: {11} materia saprei pi{9.} {2.} agion
p3 L07: gere con uenendom {2.} at ende re
p3 L08: da lei le precise risposte {1.}
p3 L09: risolu z ioni s{9.} le rile u ate
p3 L10: an te dete di f i col ta haute
p3 L11: le quali {18} per dero moien te
p3 L12: di tempo ne l rispon dere {18} la
p3 L13: sci ando di porle nouamente
p3 L14: in con si de razionr il re
p3 L15: dito del te ri torio acena
p3 L16: tomi nela nota mandatami ri
p3 L17: esce cosi tenue {1.} mis e ra{25}ile
p3 L18: a conf ronto del in tiero {10}a
p3 L19: to di {12}{1.} {2.} {18} merita mai {2.} io mi
p3 L20: lasci lusin gare a farmi
p3 L21: il min imo pregiu dizio ri
p3 L22: protest an domi {2.} quanto sare
p3 L23: per far incaso {18} uin te ruen
p4 L01: ga pregiu dizio dele mie ra
p4 L02: gioni s{20}ra sem pre a con tem
p4 L03: plazione del somo meri to di
p4 L04: {92} {93} per cui hauro sempr e la
p4 L05: pi{9.} osequioe c uen erazione
p4 L06: con speranz a sia per farmi
p4 L07: col tempo go dere gl ati dela
p4 L08: generosis ima sua mu ni fi
p4 L09: cenza {1.} incororga giu st iziaReading
# Guastalla, 24 September 1717: reading
Antonio Ferdinando Gonzaga, Duke of Guastalla, to a correspondent who is not named. Biblioteca Estense Universitaria, Autografoteca Campori, Lettera A, "Antonio Ferdinando, duca di Guastalla", cc. 15-16.
Italian: in the clear at the start and the end, and in cipher between them.
**Marks.**
- A code group is shown with its number, such as [2]. Where context gives a sense, the sense follows after "=".
- `[?]` marks a doubtful word or letter.
- Words in brackets are restored from context. The key did not give them.
- The reading keeps the writer's spelling where the key gives it.
- The writer's spaces do not always fall between words. Word division and punctuation are mine.
## Clear opening
Ricevo il gradito di Lei foglio di 15 corrente, dal quale
## Cipher text
The numbers match the clauses of `translation.md`. Page breaks fall inside clauses 6, 14 and 20.
1. in sostanza vedo [2 = che] era ritornato da' suoi beni il [12]e[11]e Trauston [?Trautson],
2. [12]s'attendevano la seguente settimana; li [12]q[10]e [1 = e] [11]o Starhemberg [12] Tra[20]s
3. aspettavano le mie risposte sul tenore delle antecedenti lettere scrittemi,
4. sopra delle quali, quanto a quello mi trovi haverle basta[?] solamente risposto lo scorso ordinario, [18 = non] lascio in [11]dd[26]plicarle
5. [2 = che] [18 = non] so qual risposta più precisa dare, [13] r[?]aie chiaramente [18 = non] mi si dica se sia o [18 = non] stata omessa la pretensione della lettera reversale,
6. come [12] [2 = che] fa l'istessissimo effetto dell'articolo undecimo della [93]richiarazione [= dichiarazione], anzi (page 2) peggiore,
7. venendo ad essere una tacita abdicazione delle mie ragioni, alla quale [18 = non] sarò mai per aderire,
8. per [18 = non] fare a me [13]am mi[c] casa un così evidente pregiudizio.
9. Però starò attendendo [2 = che] Lei mi parli chiaro [14]ve termini positivi su tale lettera reversale,
10. senza di [2 = che] [18 = non] so [2 = che] risposta dare [14][14]c[2]ela.
11. M'ha scritto [2 = che] [18 = non] si pretende dal se [18] [12] [2 = che] si pratica comunemente nelle [14][9] degl'altri feudi.
12. Le replico [2 = che] [13] l[14][9] [2 = che] s'intende concedermi sia secondo la forma [16]iou[16][26] delle antiche investiture solitamente concesse a' miei maggiori possessori del territorio [2 = che] si tratta di cedermi,
13. [1 = e] così, senza il minimo pregiudizio mio [13]som mia posterità, [18 = non] haverò difficoltà ad accettarla;
14. ma [13] vi si volessero (page 3) apporre condizioni nuove, e alle [?]avisi con tutta la maggiore distinzione [13] possa farvi le mie riflessioni
15. [?] [1 = e] [?] re [12] mi tornerà a conto, né [?sua] materia saprei più [2 = che] aggiungere,
16. convenendomi [2 = che] attendere da Lei le precise risposte [1 = e] risoluzioni sulle rilevate antedette difficoltà havute,
17. le quali [18 = non] perderò momento di tempo nel rispondere, [18 = non] lasciando di porle nuovamente in considerazione.
18. Il reddito del territorio accennatomi nella nota mandatami riesce così tenue [1 = e] miserabile a confronto dell'intiero [10]ato di [12][1],
19. [2 = che] [18 = non] merita mai [2 = che] io mi lasci lusingare a farmi il minimo pregiudizio,
20. riprotestandomi [2 = che] quanto sarò per far in caso [18 = non] vi intervenga (page 4) pregiudizio delle mie ragioni
21. sarà sempre a contemplazione del sommo merito di [92][93],
22. per cui haverò sempre la più ossequiosa venerazione,
23. con speranza sia per farmi col tempo godere gl'atti della generosissima sua munificenza [1 = e] [?] giustizia.
## Clear closing
- Intendo con molto dispiacere il mal stato di salute del Sig. Contino Lei figlio,
- comprendendo l'agitazione d'animo che Lei ne prova,
- e prego il Signore ridonare allo stesso la primiera sanità, ed a Lei ogni vero bene.
- Guastalla 24 7bre 1717.
- Ant. Ferd. Gonzaga.
## Notes
- "Trauston" and "Starhemberg" read as names. They match ministers at the imperial court in 1717: Prince Trautson and a Count Starhemberg. I have not checked this in print.
- The code groups for names and titles stay conjectures.
- Doubtful passages: page 1 line 15 ("r[?]aie"), page 3 line 4 ("riflesic[14]e i [1] risc[14]na e re [12]"), and page 4 line 9 ("incororga").Translation
# Guastalla, 24 September 1717: translation
English translation of `reading.md`, clause by clause. Brackets mark code groups and doubtful places. "?" marks a guess.
## Clear opening
I receive your welcome letter of the 15th of this month, from which
## Cipher text
1. In substance I see that [the Prince?] Trautson had come back from the family estates.
2. [Count?] Starhemberg and Trautson [?] were expected the following week.
3. They were waiting for my answers on the content of the earlier letters written to me.
4. On these, as far as I find that I have only answered them by the last post, I do not fail to send them again [?].
5. I do not know what more precise answer to give, unless I am told clearly whether the claim of the reversal letter ("lettera reversale") has been dropped or not.
6. That letter has the very same effect as the eleventh article of the declaration, and is even worse.
7. It amounts to a tacit abdication of my rights, to which I will never agree.
8. I will not do myself and my house such an obvious harm.
9. So I will wait for you to speak to me clearly, in positive terms, about this reversal letter.
10. Without that I do not know what answer to give [?].
11. You have written to me that nothing more is claimed than what is commonly practised in [the investitures?] of the other fiefs.
12. I reply to you that, if [the investiture?] that is meant to be granted to me follows the form [?] of the old investitures usually granted to my forebears, the owners of the territory that is to be ceded to me,
13. and so without the least harm to me and to my posterity, I will have no difficulty in accepting it.
14. But if they wanted to attach new conditions to it, I could put my thoughts on them to you with all the greatest care [?].
15. [Passage not fully read.] It will be to my advantage [?], and I could add nothing more on the matter [?].
16. It suits me to wait from you for the precise answers and decisions on the difficulties raised above.
17. I will not lose a moment in answering them, and I will not fail to put them up again for consideration.
18. The revenue of the territory named to me in the list you sent is so small and poor, compared with the whole [value?] of [?],
19. that it never deserves that I let myself be tempted into the least harm to myself.
20. I declare again that whatever I do, provided that no harm to my rights comes of it,
21. will always be out of regard for the high merit of [code 92 93: the Emperor?],
22. for whom I will always have the most dutiful veneration,
23. in the hope that, in time, I will enjoy the acts of that most generous munificence and [?] justice.
## Clear closing
I hear with much regret of the bad health of the young Count, your son. I understand the distress of mind that you feel. I pray the Lord to give him back his former health, and to you every true good. Guastalla, 24 September [written "7bre"] 1717. Antonio Ferdinando Gonzaga.
## Gist
The duke writes to an agent at the imperial court, or in touch with it. The court has offered the duke a territory. The duke refuses to sign a "reversal letter" that would give up other claims. The duke will accept the territory only on the old terms of investiture. The territory's income is too small to justify any loss of rights.Key: key.tsv
05 Sources
- Biblioteca Estense Universitaria, Modena, Autografoteca Campori, Lettera A, “Antonio Ferdinando, duca di Guastalla”, cc. 15–16 (record and scans, licence CC BY-NC-SA); the scans are not reproduced here.
- Prabal Gupta, issue #329, and his repository prabal-rje/branicki-1757 (folder
guastalla-1717, commit af80f5e, CC BY 4.0): the transcription, the key, the reading and his notes.
The documentation, the key, the transcription, the reading and the check are in targets/guastalla1717.
Cite this page
Prabal Gupta and Daniel Bourdeau, “The Duke of Guastalla on a “lettera reversale”, 24 September 1717”, Cyphersolver, posted 8 November 2026, https://cyphersolver.com/guastalla1717.html.