The Controversial Replicaof Leonardo da Vinci

Dr. Roberto Guatelli

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Introduction

Dr. Roberto Guatelli was a renowned world expert of Leonardo da Vinci and specialized in building working replicas of da Vinci. He had built countless such replicas with four assistants.
Early in 1951 IBM hired Dr. Guatelli to continue building such replicas. They had organized a traveling tour of the machines, which was displayed at schools, offices, labs, museums and galleries. In 1961 Dr. Guatelli left IBM and set up his own work shop in New York.

On February 13th 1967 an amazing discovery was made by American researchers working in the National library of Spain, Madrid. They had stumbled upon 2 unknown works of Leonardo da Vinci know as the "Codex Madrid". There was much excitement regarding this discovery and the public officials stated that the manuscripts "weren't lost, but just misplaced".

digitally enhanced picvture of the codex page

In 1967, shortly after the discovery of the "Codex Madrid", Dr. Guatelli flew to the Massachusetts university to examine its copy.When seeing the page with the calculator he remembered seeing a similar drawing in the "Codex Atlanticus". Putting the two drawings together Dr. Guatelli built the replica later in 1968.

It was displayed in the IBM exhibition.

After some years controversy about the correctness on the replica arised and IBM removed the replica from its exhibitions

Description(1)

replica at the IBM exhibition

The text beside the replica said:

Device for Calculation: An early version of today's complicated calculator, Leonardo's mechanism maintains a constant ratio of ten to one in each of its 13 digit-registering wheels. For each complete revolution of the first handle, the unit wheel is turned slightly to register a new digit ranging from zero to nine. Consistent with the ten to one ratio, the tenth revolution of the first handle causes the unit wheel to complete its first revolution and register zero, which in turn drives the decimal wheel from zero to one. Each additional wheel marking hundreds, thousands, etc., operates on the same ratio. Slight refinements were made on Leonardo's original sketch to give the viewer a clearer picture of how each of the 13 wheels can be independently operated and yet maintain the ten to one ratio. Leonardo's sketch shows weights to demonstrate the equability of the machine.

The whereabouts of the replica today is unknown. Possibly it is somewhere in one of IBM's storages.
Joseph Mirabella still owns the work shop in New York, with many of the replicas at hand.

Specifications

Release history

1968 First release of replica

1	text based on article from Erez Kaplan.
2	Codex photo courtesy of RRZN/RVS, University of Hannover, Germany.
3	Replica photo courtesy of Mr. Joseph Mirabella, New York, USA.
4	Bibliography: "The History of Computing" - Marguerite Zientara. "Think" magazine - Volume 50 #6, December 1984. "Codex Madrid I" - Leonardo da Vinci. "Leonardo da Vinci - Engineer and Architect" - The Montreal Museum of Fine Arts 1987
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Leonardo da Vinci's Adding Machine

USA 1968 - replica