Is There Something Missing from the Antikythera Mechanism? Was It a Mechanical Planetarium–Positioner? Or a Luni-Solar Time Calculator Device? Reconstructing the Lost Parts of b1 Gear and Its Cover Disc

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

Final Recommendation: ACCEPT as it is.

The manuscript is:

original,

methodologically robust,

well written,

mechanically and logically convincing, and

significant for the continuing scholarly study of the Antikythera Mechanism.

 

The article is worth publishing because it:

Provides original, evidenced, mechanically grounded discoveries

Fills seemingly functional gaps in an acceptable scheme

Introduces a powerful, reproducible, experimental methodology

Challenges widely held assumptions with substantive evidence

Produces a coherent, complete, and testable reconstruction

Advances the field’s understanding of ancient Greek scientific instruments

It significantly enhances our understanding of ancient Greek computational design

It challenges the prevailing “planetarium” paradigm with strong mechanical arguments

 

Most modern reconstructions assume the Mechanism included planetary pointers.

This has become a dominant narrative, but not one strongly supported by the mechanical record.

 

This paper provides:

logical mechanical critiques

torque and handling analyses

inscription-based arguments

The proposed reconstruction shows:

a more advanced understanding of tropical-year tracking

explicit management of solar calendar

integration of lunar-age display

full implementation of eclipse-related cycles

This suggests the Mechanism was closer to a complete time-handling instrument, not a partial astronomical display.

Publishing this expands our knowledge of:

ancient Greek calendar science

eclipse prediction technologies

mechanical engineering capabilities

Hellenistic scientific instruments

In short, it advances the Antikythera Mechanism research in a meaningful, evidence-based, and testable way — exactly what a publishable scientific contribution should do.

I am sure the authors understand that there are other views, equally plausible and acceptable, based on original ancient Greek and Latin texts, including the manual of the mechanism.

Author Response

Comments 1 and Suggestions for Authors

Final Recommendation: ACCEPT as it is.

The manuscript is:

original,

methodologically robust,

well written,

mechanically and logically convincing, and

significant for the continuing scholarly study of the Antikythera Mechanism.

 

The article is worth publishing because it:

Provides original, evidenced, mechanically grounded discoveries

Fills seemingly functional gaps in an acceptable scheme

Introduces a powerful, reproducible, experimental methodology

Challenges widely held assumptions with substantive evidence

Produces a coherent, complete, and testable reconstruction

Advances the field’s understanding of ancient Greek scientific instruments

It significantly enhances our understanding of ancient Greek computational design

It challenges the prevailing “planetarium” paradigm with strong mechanical arguments

Most modern reconstructions assume the Mechanism included planetary pointers.

This has become a dominant narrative, but not one strongly supported by the mechanical record.

 

This paper provides:

logical mechanical critiques

torque and handling analyses

inscription-based arguments

The proposed reconstruction shows:

a more advanced understanding of tropical-year tracking

explicit management of solar calendar

integration of lunar-age display

full implementation of eclipse-related cycles

This suggests the Mechanism was closer to a complete time-handling instrument, not a partial astronomical display.

Publishing this expands our knowledge of:

ancient Greek calendar science

eclipse prediction technologies

mechanical engineering capabilities

Hellenistic scientific instruments

In short, it advances the Antikythera Mechanism research in a meaningful, evidence-based, and testable way − exactly what a publishable scientific contribution should do.

I am sure the authors understand that there are other views, equally plausible and acceptable, based on original ancient Greek and Latin texts, including the manual of the mechanism.

Responce 1

We thank the anonymous Reviewer 1 for his positive feedback.

Reviewer 2 Report

Comments and Suggestions for Authors

A well-documented research work with strong arguments for a functioning bronze reconstruction of lost parts of gears b1 of the Antikythera Mechanism, based only on its mechanical remains. The hypothesis of two missing mandatory indicators is based on the significant difficulties a user of AM faces without them, as shown by its models. The authors sought to understand the Ancient Craftsman's methods before proceeding with their functional reconstruction of AM according to a Constructional protocol. Finally, their arguments against the planets' gearing hypothesis are very persuasive.

I suggest using "planets' gearing" instead of "planets gearing" everywhere it is needed.

Line 608 correction: "as shown" instead of "as sown".

Author Response

Comments 1 and Suggestions for Authors

A well-documented research work with strong arguments for a functioning bronze reconstruction of lost parts of gears b1 of the Antikythera Mechanism, based only on its mechanical remains. The hypothesis of two missing mandatory indicators is based on the significant difficulties a user of AM faces without them, as shown by its models. The authors sought to understand the Ancient Craftsman's methods before proceeding with their functional reconstruction of AM according to a Constructional protocol. Finally, their arguments against the planets' gearing hypothesis are very persuasive.

I suggest using "planets' gearing" instead of "planets gearing" everywhere it is needed.

Line 608 correction: "as shown" instead of "as sown".

Responce 1

We thank the anonymous Reviewer 2 for the positive feedback.

Reviewer 3 Report

Comments and Suggestions for Authors

The paper is interesting but it lacks clarity and style, resulting in an unclear paper. I would suggest to improve the introduction, defining since the beginning all the terms used in the text, also providing additional schematic figures on the whole Mechanism. So much is given for granted regarding the functioning of the Antikythera Mechanism, and specialised terms are used without proper definition. Also the methodology should be better explain and clarify (it was never explicitly mentioned whether you physically reconstructed or not the Mechanism, leaving the reader with doubts). A full and significant revision of the structure of the paper is necessary, and academic style and coherence should be improved notably. The figures/tables/images/schemes are appropriate but sometimes they are missing links with the main text. 

Comments for author File: Comments.pdf

Comments on the Quality of English Language

To be improved, also adding coherence in typing style (capitalisation, italic, citations, etc.)

Author Response

Comments 1 and Suggestions for Authors

The paper is interesting but it lacks clarity and style, resulting in an unclear paper. I would suggest to improve the introduction, defining since the beginning all the terms used in the text, also providing additional schematic figures on the whole Mechanism. So much is given for granted regarding the functioning of the Antikythera Mechanism, and specialised terms are used without proper definition. Also the methodology should be better explain and clarify (it was never explicitly mentioned whether you physically reconstructed or not the Mechanism, leaving the reader with doubts). A full and significant revision of the structure of the paper is necessary, and academic style and coherence should be improved notably. The figures/tables/images/schemes are appropriate but sometimes they are missing links with the main text.

Comments on the Quality of English Language. To be improved, also adding coherence in typing style (capitalisation, italic, citations, etc.)

Responce 1

We thank the anonymous Reviewer #3 for the valuable comments and guidelines. We have revised our manuscript in accordance with the Reviewer’s suggestions. The revised manuscript (docx file) is provided in Track Changes mode to clearly indicate corrections to the English language, as well as text reformulations and revisions. All of Reviewer #3’s comments listed in peer-review-52678145.v1.pdf have been addressed and incorporated into the revised manuscript.

 

Round 2

Reviewer 3 Report

Comments and Suggestions for Authors

Thank you for addressing the issues highlighted in the previous report. I will accept it for publication after minor revisions. Again I will suggest to reframe the structure including a methodological section for clarity of reading. I would suggest also to further contextualise the ancient craftsman, where he would have lived? when? which were his tools and theoretical knowledge? Also, can you make clear if the 'Personal Constructional Characteristics' (PCC) is sometimes you invented or did you gather from somewhere else?

Comments on the Quality of English Language

To be checked by mother tongue

Author Response

Comments 1: Again I will suggest to reframe the structure including a methodological section for clarity of reading.

Response 1: The structure of the paper follows:

1. Introduction

1.1. A Brief History of the Antikythera Mechanism

1.2. The Measuring Units of the Antikythera Mechanism

2. Materials and Method

2.1. Present Day Missing Parts of the Antikythera Mechanism

2.2. Clues for the Hypothesis of the Planets’ Rotating Spheres on the Antikythera Mechanism. Objections and Contradictions

2.3. Remains of Mechanical Parts on the Gear b1

2.4. The b1 Cover Disc of the Antikythera Mechanism’s Front Face

3. Results

3.1. The Personal Constructional Characteristics (PCC) of the ancient craftsman

3.1.1. PCC-1: The Stabilization of the Moving Parts

3.1.2. PCC-2: The Ω-Plates and the Thin Sheet Strips

3.1.3. PCC-3: Using Spacers for the Gears’ Support

3.1.4. PCC-4: The Pointers Rotated on Their Calibrated Dial

3.2. Reconstructing Lost Mechanical Parts of the b1 Gear by Applying the Constructional
Characteristics of the ancient craftsman

3.2.1. Measuring procedures that must have been present in the AM but are not preserved

3.2.2. First Necessary (Not Preserved) Measurement Process

3.2.3. Second Necessary (Not Preserved) Measurement Process

4. Discussion
5. Conclusions

 

The structure follows the format suggested by the journal, and it would be difficult to alter this structure without conflicting with the required format.

1. Introduction: The history of the Antikythera Mechanism (AM) is outlined, including the use and the operation of the device.
2. Materials and Methods: This section describes the current condition of the AM and the prevailing understanding of its function. We present scientific arguments challenging certain hypotheses that are not well-supported, justified or accepted in mechanical point of view. The analysis focuses on the main gear (b1) of the AM, which retains some preserved mechanical remnants. We also address what is most probably missing from this gear.
3. Results: We report the findings from our study of AMRP CT scans and the visual photographs of the fragments. Our analysis leads to the identification of which parts should have been attached to the b1 gear, though these components are now lost. Additionally, we introduce two previously unrecognized operations that have not been preserved or discussed until now. These operations offer a clearer understanding of the original state of the Mechanism before it was damaged by seawater and time.
4. Discussion: We critically examine the hypothesis regarding the planet’s spheres and pointers, arguing that it is flawed and not supported by mechanical principles or the results from the PCC analysis.

 

Comments 2: I would suggest also to further contextualise the ancient craftsman, where he would have lived? when? which were his tools and theoretical knowledge?

Response 2: There is no clear information available regarding the identity of the ancient craftsman who created the Antikythera Mechanism. In a previous publication, we identified the likely starting date for the initial calibration position of the Mechanism’s pointers as 22/23 December 178 BC (Voulgaris et al., 2023a). This suggests that the craftsman likely lived, at least as an adolescent or young adult, before/after this period. Notably, Hipparchos of Rhodes (190 − 120 BC) lived in Alexandria and Rhodes, would have been contemporary to this period.

On the contrary, scientists such as Posidonius of Rhodes (c. 135 − c. 51 BC) and Geminus (1st century BC − c. 50 BC) lived significantly later, making them unlikely candidates.

Archimedes of Syracuse (287 − 212 BC) has also been proposed as the creator of the Mechanism (Freeth 2014; Carman and Evans 2014); however, analysis of the Back Cover Inscription Part-2, renders this hypothesis improbable (Voulgaris et al., The Reconstruction of the Antikythera Mechanism Instruction Manual after a Diligent Study and Analysis of the Back Cover Inscription, Parts 1 and 2, 2026, currently in 2^nd round of review).

To date, the identity of the craftsman who created this remarkable geared device remains unknown.

- Regarding the tools required for constructing the AM, a craftsman from around 180 BC would have needed a range of specialized instruments. These would have included iron files, a bow drill or even better a stable drill, iron (hardened) drills with diameters ranging from 0.8mm to 5mm, a lathe for processing the axles, and a good quality dividing machine to divide circular plates into equal parts so as to create gears with specific numbers of teeth, including prime numbers such as 53, 127, and 223.

The bow drills, dating back to around 450 BC and depicted on ceramics, as well as the Ptolemaic vertical lathe from the tomb of Petosiris (c. 300 BC), could be seen as the precursors to the tools used for the AM's construction (Voulgaris et al., 2019a; https://antikytheramechanism.pro/).

- Undoubtedly the craftsman of the Mechanism was highly skilled in geometry, mechanical design, engineering, constructions, and likely astronomy. He would also have required exceptional finger dexterity and, most importantly, a great deal of patience (Voulgaris et., al 2019a). At the time, these disciplines were studied by the ancient Greek “Geometers” and astronomy held particular significance in both social and religious life, especially regarding the lunar phases (synodic cycle). This is one of the reasons that the AM was a time measuring device based mostly on the lunar cycle (Voulgaris et al., 2025).

 

- Carman C.C.; Evans J. On the epoch of the Antikythera mechanism and its eclipse predictor. Arch. Hist. Exact Sci., 2014, 68, 693–774.

- Freeth T. Eclipse prediction on the ancient Greek astronomical calculating machine known as the Antikythera Mechanism. Plos One, 2014, 9(7), e103275.

- Voulgaris A.; Mouratidis C.; Vossinakis A. Ancient Machine Tools for the construction of the Antikythera Mechanism parts. Digital Applications in Archaeology and Cultural Heritage Journal, 2019a, 13, e00092.

- Voulgaris A.; Mouratidis C.; Vossinakis A. The Initial Calibration Date of the Antikythera Mechanism after the Saros Spiral Mechanical Apokatastasis”, Almagest, 2023a, 14(1), 4–39.

 

Comments 3: Also, can you make clear if the 'Personal Constructional Characteristics' (PCC) is sometimes you invented or did you gather from somewhere else?

Response 3: The Personal Constructional Characteristics (PCC) of the ancient craftsman were clearly identified through the study of the AMRP X-ray volumes/CT scans, as well as detailed visual examination and visual photographs of the fragments. For example, in order to secure a gear to its shaft, the craftsman consistently used a perpendicular pin inserted through the shaft just above the upper surface of the gear. Numerous such pins positioned above gears have been detected on fragments A, B and D. This specific stabilization method has been adopted in all of our functional reconstructions, with every gear fixed in the same manner.

Notably, the craftsman avoided securing gears to their shafts using solder or glue for bronze (tin-lead alloy), although such materials were well known in antiquity. This method of fixation is mechanically unstable and doubtful, especially, if the part is moving or rotating, or carries torque/pressure, even by modern standards.

In our reconstructions, we made no arbitrary modifications to the PCC in order to accommodate construction scenarios that are inconsistent with these observed characteristics. Furthermore, we did not alter the original dimensions - particularly axle diameters - to support any specific hypothesis. For instance, the partially preserved central axis b_in has a diameter of approximately 4.25 mm. This dimension imposes a strict mechanical limitation on shaft length: bronze axles/shafts longer than about 60 mm would be susceptible to torsional deformation. Consequently, hypotheses that require this axis to be approximately 100-120 mm in length (as would be necessary for planetary display models within the AM) are mechanically unacceptable, even by the engineering standards of the period.

Comments 4: To be checked by mother tongue

Response 4: We made additional corrections in the text.

 

We thank Anonymous Reviewer #3 for these additional comments and suggestions.

The first author

Aristeidis Voulgaris

Author Response File: Author Response.pdf