To keep away enemies
A Sneakoscope is a type of Dark Detector that looks like a glass spinning top. It lights up, spins, and whistles if someone is doing something untrustworthy nearby.
The Sneakoscope was invented in the eighteenth century by Edgar Stroulger.
Ronald Weasley (Ron) purchased a "pocket" Sneakoscope in Egypt in 1993 as a thirteenth birthday present for Harry Potter. Ron's brother Bill said it was just a piece of rubbish sold for tourists and did not work as it was whistling at their supper table. However, he had not realised that Fred and George had put beetles in his soup. It also lit up when Ron was tying Harry's birthday package to Errol's leg, as he was not supposed to use the old owl for long journeys. Later that year, Harry's Sneakoscope started whistling on the Hogwarts Express when Scabbers was nearby, as Scabbers was really Peter Pettigrew (which might help explain the previous occurences as well). Harry had to keep the Sneakoscope in a pair of Uncle Vernon's old socks to keep the whistling quiet.
"Professor Moody"-Mad Eye Moody- had a large Sneakoscope in his office in Harry's fourth year at Hogwarts. He had to disable it because, he claimed, it was extra-sensitive and would whistle at any deceit as far off as a mile — not to mention students lying about their homework. Regardless of the truth of this claim, it would certainly have been activated by "Professor Moody" himself, as he was Barty Crouch Jr. in disguise.
A few Sneakoscopes (along with other detection devices) were present in the Room of Requirement while Dumbledore's Army was using it to practise. Sadly, they proved of little help to the D.A. since when Professor Dolores Umbridge finally discovered where they were.
The contraption later alerted Harry, Ron, and Hermione about the Snatchers outside of their tent after accidently saying the Dark Lord's name even though it was Tabooed. Unfortunately, it also alerted the Snatchers that the trio was in the tent.
Behind the scenes
- A Sneakoscope can be seen on the flash version of J. K. Rowling's Official Site.
- Sneakoscopes can be purchased at The Wizarding World of Harry Potter and Warner Bros Studio Tour London - The Making of Harry Potter as a novelty toy.
- Harry Potter and the Prisoner of Azkaban (First appearance)
- Harry Potter and the Prisoner of Azkaban (film) (Deleted scene)
- Harry Potter and the Goblet of Fire
- Harry Potter and the Order of the Phoenix
- Harry Potter and the Half-Blood Prince (Mentioned only)
- Harry Potter and the Deathly Hallows
- The Wizarding World of Harry Potter
- J. K. Rowling's Official Site