Quote Originally Posted by Sprockets View Post
Brian Denyer

Hello, I have just, belatedly come across this thread. Sally Thompson sounds quite a woman, so I searched through all British patents from the beginning (1617), and unfortunately failed to locate the patent. Have you possibly misspelled her name? I did check for Thomson from 1617 to 1850, but still nothing. Did you find the reference from another publication?

I have a suspicion that such indicating locks were known before patents were even originated, as I vaguely remember seeing a very old lock somewhere, a long time ago!
Regards,
Martin Cummins.
Firstly, not all the older patents have been digitised, so Internet searches do not find them.
Pre-1851 or 1852, patents were not numbered. A new Commissioner of Patents had all existing records of patents for invention put into chronological order and retrospectively numbered, though these numbers were not published for some years afterwards.
Sally Thompson's patent of 13 November 1838 is well-known for being the only early lock patent granted to a woman.
This lock, however, appears to conform more closely to Meighan's alarum lock,'invented about 1836'. See PRICE Treatise on fire and thiefproof depositories pp.446-450. 'They are more curious than useful and none have ever come into general use'.