Barron's patent claimed the
principle of
the double-acting movable detainer. Barron described two possible realisations of the principle: the form of lever lock (as it would now be called) which he and his family used, with the stump on the tumblers (Barron's term) and the pockets and gates in the bolt lathe, and the form made popular by, and commonly associated with, the name of Chubb. This realisation, which proved more versatile, has a stump fixed to the bolt lathe and pockets and gates in the levers. Other realisations are possible.
It was soon found that with only 2 levers (without flush bellies), Barron's realisation was not as secure as he had believed, though his locks also contain wards which are a considerable hindrance to defeat, especially in small sizes.
Bramah described his lock in a dissertation. Hardcopy reprints can be bought today:
https://www.amazon.co.uk/Dissertation-C ... 1385347325Copies are also online; facsimiles of the original printing are somewhat difficult to read, even on paper.
https://en.wikisource.org/wiki/A_Disser ... ocks_(1785)
https://en.wikisource.org/wiki/A_Disser ... ocks_(1815)
Google requires readers to sign in:
https://play.google.com/store/books/det ... AAJ&rdot=1Locks using levers continue to be made in some parts of the world, in a range of functions, qualities, and security, ranging from trivial privacy to suitable for the Bank of England.
Pin tumbler locks using single-acting tumblers were known in the ancient world, from four millennia ago. They were brought to the notice of Europeans, and Americans, by the publication of Vivant DENON's record of Egypt with Napoleon's expedition. It appeared in France 1803, and London 1805:
Travels in Upper and Lower Egypt: In Company with Several Divisions of the French Army, during the Campaigns of General Bonaparte in that CountrySeveral editions have been published, including a Kindle ebook.
Following this, inventors on both sides of the Atlantic began inventing metal versions of the pintumbler lock, with double-acting tumblers. American, Abraham Stansbury obtained patent [BP2851] in 1805. The lock was not a commercial success in Britain or America where he obtained a US patent in 1807 — the first patent to be granted for locks in America.
Through the 1850s-60s Linus Yale Snr and Jnr developed their versions. Yale Jnr achieved commercial success by combining the pintumbler with the cylinder lock principle invented by (though not patented) Joseph Bramah.
Lever locks can be made with relatively simple machinery, and (depending on materials) can be both robust and weather-resistant. Around the world, there is little standardisation of sizes.
Not only are they not susceptible to 'bumping', drill points are not obvious, as when in use, except for padlocks, the lock is largely out of sight.
Bramah locks are still made, as the company is the oldest patent lockmaker still in business, having been trading continuously since 1784. They are, for example, among the few locks approved by the government in Britain, for securing explosive stores.
