These days we use the term copper-bottomed to describe something that is certain, genuine, trustworthy and unlikely to fail. The derivation of our phrase is equally copper-bottomed. It is all to do with the treatment of ships.
In the days of wooden ships, maintenance was a considerable headache. The activities of one creature in particular, Toredo worms, were positively migrainous. These saltwater clams have a particular appetite for boring into wood which has been immersed in seawater. Over time, of course, if their actions are not detected or treated, then the wood can disintegrate, causing a bit of a problem if you are sailing the seven seas.
To counteract the problem, the British Navy, in 1761, started a process of adding copper plating to the underside of the hulls of their ships. So, the ships were literally copper-bottomed. By March 1781, at least according to the London Magazine who reported the rather self-satisfied remarks of Admiral Keppel, it was job done, despite the laggardly behaviour of Lord Sandwich; “he reproached Lord Sandwich with having refused to sheath only a few ships with copper at his request, when he had since ordered the whole navy to be sheathed.”
There were other benefits to this enhancement to the engineering of the fleet of the British navy. Their copper bottoms meant that the speed through which they travelled through the water increased and their manoeuvrability was enhanced, both features contributing to the fleet’s naval hegemony.
But there was a down-side, isn’t there always?
The copper plates were often attached to the hulls using iron nails. The combination of copper and iron together with seawater creates the perfect conditions for something called electro-chemical corrosion, where electrons from other compounds are attracted to the ions in the metal allowing the seawater to corrode the metal. This was almost as dangerous to the mariners as worm-infested timbers and so to resolve the problem iron nails were replaced by copper ones in a process known as copper-fastening.
In the late 18th century a boat which was copper-bottomed and copper-fastened was the real deal. For confirmation of this statement you only have to look at the Hull Advertiser for July 9th 1796 where it announces, “she is copper-fastened and copper-bottomed, and a remarkable fine ship.”
It was not too much of a stretch to see how copper-bottomed could move from a prosaic description of the features, and thereby enhanced seaworthiness, to a figurative sense of trustworthy, genuine or reliable. One of the first instances of its usage in a figurative sense appeared in the satirical periodical created by Washington Irving and his brother, William, called Salmagundi; or the Whim-whams and Opinions of Launcelot Langstaff & Others. Launched at the start of the 19th century Irving used it to lampoon New York culture and politics. In the edition of May 16th 1807 he wrote, “..except by the celebrated eagle, which flutters his wings over the copper-bottomed angel at messrs. Paff’s in Broadway.”
Irving was clearly on a roll that year, ascribing in the edition for November 11th the name, well known to aficionados of Batman, of Gotham to New York, apparently as an analogy to the supposed stupidity of the residents of a village in Nottinghamshire by the same name. In 1894, Robert Louis Stevenson wrote in the Ebb-Tide, which he co-authored with his stepson, Lloyd Osborne, “The real, first-rate, copper-bottomed aristocrat.”
The term was sufficiently established in the vernacular by 1890 to appear in Slang and its Analogues, a seven volume meisterwerk compiled by J S Farmer and W E Henley. There they helpfully define the term thus; “in mercantile circles, the expression has become popularly current, in a figurative sense, to signify the highest commercial credit; and first-class, first-rate.”
Copper-fastened, a different technique, as we have seen, has also been used figuratively but not until the middle of the 20th century. The Evening Independent in November 1848 wrote; “we had some striking examples of what happens when a guy gets so big for his britches that any pal of his is automatically a copper-fastened genius.” The sense seems to slightly different, denoting certainty rather than trustworthiness.