Joseph Bramah: The 1784 Lock, the Challenge Padlock, and the Hydraulic Press

Early Life

Grace's Guide gives Bramah's birth as 13 April 1748 at Stainborough, Yorkshire. It adds a query that the true day may be the 2nd. The Linda Hall Library and Wikipedia give 13 April. His father, also Joseph, was a farmer. Grace's Guide says Bramah worked on the farm until an injury turned him toward woodworking. He moved to London and found work as a cabinet-maker.

His first patent came out of that work. While fitting water closets, he found faults in the model he was installing. He designed his own and patented it in 1778, when he was described as a cabinet-maker of Cross Court, Carnaby Market. He later worked from a shop in Denmark Street, St Giles's. In 1783 he married Mary Lawton of Mapplewell, near Barnsley. The couple lived at 124 Piccadilly and later in Pimlico (Grace's Guide).

The 1784 Lock Patent

In October 1783, Grace's Guide records, Bramah joined the Society of Arts, where he attended technical discussions about locks. His lock patent, No. 1430, is dated 21 August 1784 (Grace's Guide; Wikipedia). The same year he started Bramah and Co. In 1785 he published A Dissertation on the Construction of Locks. Grace's Guide also records that the lock patent was extended in 1798 for a further 14 years.

The principle stays simple at the level used here. The key is a tube with slots of different depths cut into its end. Pushing it in moves a set of sliders to the depths set by the slots, and only then can the key turn. The Linda Hall Library says most Bramah locks of this type had four to six sliders.

Maudslay and the Challenge Padlock

The lock needed exact parts, and that made production the real difficulty. According to the Linda Hall Library, Bramah hired the 18-year-old Henry Maudslay in 1789 and set him the challenge of helping to design and build a lock that could not be picked. Wikipedia says the two created a number of machine tools that made the locks more efficient to produce. Those tools were useful in other trades too. Maudslay left the company in 1797 (Grace's Guide) and became one of the leading precision engineers of the next generation.

The Linda Hall Library dates the result, the challenge padlock, to 1790. Its key had 18 slots cut into the end to work 18 sliders, far more than an ordinary Bramah lock. The firm displayed it in the shop window with a placard that read: "The Artist who can make an Instrument that will pick or Open this Lock shall Receive 200 Guineas the Moment it is produced." It stayed there, unopened, through Bramah's death in 1814 and into his sons' management of the firm. The lock survives at the Science Museum in London. Wikipedia notes that the lock was rebuilt after 1851 and now has 13 steel slides. Originally it had 18 iron slides and one central spring.

A Science Museum Group object is titled "Bramah padlock and key (1801)," and some accounts take it to be the challenge lock. It is not yet confirmed whether that object and the window lock are the same. This article therefore attributes the 1790 date to the Linda Hall Library.

1851: The Lock Is Opened

In August 1851 the American locksmith Alfred Charles Hobbs, in London for the Great Exhibition, opened the challenge lock under agreed conditions. The Linda Hall Library says it took him 51 hours spread over 16 days with specially made tools. Grace's Guide says about 45 hours. After an argument about the circumstances, the prize was paid. The Linda Hall Library judges that the difficulty Hobbs had, if anything, strengthened the reputation of Bramah & Sons.

The Hydraulic Press and Other Work

Bramah's patent No. 2045 of 1795 described a hydraulic press, and Grace's Guide calls it his most important patent. Grace's Guide also records:

• several rotary-pump and engine patents;
• a fire-engine patent (1793);
• a beer pump (1797);
• a planing machine patent (1802), whose machine was supplied in 1805 to the Royal Carriage Department at Woolwich and was reportedly still working in 1881;
• a patent for the sequential numbering of bank notes (1806).

Between 1790 and 1793 he also worked as a civil engineer on new waterworks at Norwich. Around 1806 he built a new works on what is now Ebury Street in Pimlico.

Death

In 1814 Bramah was supervising his hydraulic machinery at Holt Forest in Hampshire, where it was used to pull up large trees by the roots. There he caught a severe cold that settled on his lungs. He died at his house in Pimlico on 9 December 1814 and was buried at Paddington churchyard (Grace's Guide). The Linda Hall Library names the burial place as St Mary's, Paddington Green. No portrait of him was known to exist in 1862, when an engraving of eminent men of science showed him with his back turned. Grace's Guide reproduces a portrait that was later identified and verified as genuine.

Legacy

Bramah's lock showed a new standard for security: a lock should resist a skilled, patient attacker, not just a casual one. The public challenge turned that standard into a test anyone could see. The firm's need for accurate, repeatable parts helped to train engineers such as Maudslay. For the mechanism and the firm's later locks, see Bramah lock. For the cylinder-lock tradition that followed, see pin tumbler lock, Linus Yale, and padlock.

Related Topics

• Bramah Lock
• Alfred Hobbs
• Robert Barron
• Jeremiah Chubb
• Padlock
• Locksport

Sources