Why do French locks 'double' lock, and are any examples of unusual drill pin shapes?

[Brian Morland]

There is a nice feature in the current 'History of Locks Journal' about pre-industrial European locks speculating on how these locks could rival the later high security lever locks. Not only did they have double throw mechanisms but hey also contained other 'secrets' which unless the opening sequence was known they were unlikely to be opened even if you had the correct key.

The Key page in the next issue (due out in march) includes some illustrations from Art du Serrurier. Par M. Duhamel du Monceau. M. DCC. LXVII.(1767). This is a french book and is believed to be the earliest wholly on the subject, has just been received back from specialist conservators where it was radiated to neutralize latent fungi in the paper.

Pics of a star shaped key and its matching star shaped drill pin. Several of these keys/ locks will be exhibited at the Lock Expo in Nottingham in March 2018.

[lorddlm2]

Hi there Brian

Thank you so much for these images - it is particularly exciting to see the photos of the star and spade shaped drill pins. Do you think there is significance to playing cards here (ie. are there also heart and diamond shaped drill pins?).

So the term is 'double-throw'? Do you know of a reason why this feature was included?

Many thanks again

Daniel

[Brian Morland]

Some were double throw, some were triple throw. Sometimes the key would have to be turned a number of times and the bolt only shoot on the last turn of the sequence. Possibly there were sequences that were associated with the locksmith, his client or even the lock type. There are quite a number of variants in the collection and amazingly almost as many variations in the action or the sequence; the secret needs to be known even if you have the key - the picklock approach would be very challenging.

Regarding the drill pin issue; the shapes do include those typically seen on cards but I'm not aware of any correlation or association. I would be interested if a connection is found, perhaps others know something more concrete in this regard.