“Sam walks by Big Ben at three o’clock, looks up at its face, and thinks, ‘It is now three o’clock’. However, unbeknownst to Sam, Big Ben malfunctioned and stopped precisely twelve hours ago.”
So maybe Sam just got lucky? But what would have happened if he’d passed by at 12:55? Such happenstances are examined in great detail in a recent paper for Philosophia, volume 39, number 3 (2011), pp. 547-561 – newly adding to the debate regarding the concept of Anti-Luck.
The paper also features Sam’s fortuitous experiences with a misbehaving calculator which manages to tell him that 131,071 is a prime number (even though its circuits have already been irreparably damaged by his neighbour’s hazardous experiments with plasma discharges). And, when he picks up a book on homeopathy, it (quite luckily) informs him that water is H2O.
For comprehensive details see the full paper: Anti-Luck Epistemologies and Necessary Truths* by professor Jeffrey Roland and professor Jon Cogburn of the Philosophy Department at Louisiana State University, US.
 Strictly speaking, Big Ben can’t visually display the time – since it’s a bell, not a clock. The Clock Tower (recently renamed The Elizabeth Tower) at the Palace of Westminster does have a clock, called the Great Clock of Westminster, which some, mistakenly (sometimes along with the tower itself) call Big Ben.
 Marie von Ebner-Eschenbach is credited (at least by Wikipedia) as being the source of the phrase : “Even a stopped clock is right twice a day.”
(Quoted from professor Cogburn’s Personal Website)