P-p-pick up a pen gwyn

QUESTION Why does the word penguin come from the Welsh for white head when these birds have black heads?

The word penguin did not originally denote the flightless birds of the Southern hemisphere, but the extinct great auk ( Pinguinus impennis).

This bird was unrelated to penguins, but was similar in appearance and habits. A 2 ft black-backed, white-bellied diving bird, it didn’t have a white head, but had a white patch above its eyes.

They were not named for their appearance, but after their major breeding site: a high, guano-whitened headland on White head island near Newfoundland in the North Atlantic. Smaller auks, including the little puffin, still nest there.

Great auks were found in large numbers on White head in the 16th century, hundreds of years before europeans misnamed the unrelated bird of the far Southern oceans.

The demise of the great auk was a sad, but familiar, tale. They waddled awkwardly on land, making them easy prey, and were hunted ruthlessly for their feathers, meat, fat and oil. The last living bird was recorded in 1852.

There are competing theories surrounding the etymology of the word penguin: it was derived from the Welsh pen gwyn meaning white head; it’s a derivative of the Latin word pinguis meaning fat; or it comes from the english phrase pin wing.

There is little evidence to substantiate pin wing, which was only known from the 19th century. The Latin derivation is more plausible as penguins and great auks have a thick layer of fat under the skin that was valued by hunters.

The favoured derivation is the Welsh one, supported by the fact pen gwyn closely matches the earliest known forms of the word. Penguyn, pengwin, pengwyn and penguin date to the 16th century. Leah White, Winchester, Hants. QUESTION Is folie a deux a genuine disorder? FoLie a deux — which means folly of two or madness shared by a couple — is a well-established psychiatric disorder.

It is a delusion or mental illness shared by those in close association. The

International Classification Of Diseases defines it as ‘induced delusional disorder’. The Diagnostic And Statistical Manual Of Mental Disorders refers to it as a shared psychotic disorder.

It was first described in a famous 1877 paper by French physicians ernestCharles Lasegue and Jules-PhilippeJoseph Falret in which they presented seven case histories. They broke it down into several syndromes in which mental symptoms, particularly paranoid delusions, are transmitted from one person to one or more others with whom they are intimately associated.

Psychiatrists have adopted terms such as communicated insanity, contagious insanity, infectious insanity, psychosis of association and induced psychosis.

It can involve psychopaths such as Ian Brady and Myra hindley or Bonnie and Clyde. It has also been used to describe doomed lovers such as Sid Vicious and Nancy Spungen.

The diagnosis has been invoked as a legal defence — with mixed results.

In an infamous murder trial in Auckland, New Zealand, in 1954, two teenage girls,

Juliet hulme and Pauline Parker, were accused of bludgeoning Parker’s mother to death because she opposed their lesbian relationship.

Lawyers for the defence argued the girls suffered from folie a deux and were not responsible for their actions. The jury rejected the defence and the pair were sent to prison. This case was the subject of the 1994 Peter Jackson film heavenly Creatures, starring Kate Winslet.

In 2014 in Waukesha, Wisconsin, 12year-old girls Anissa Weier and Morgan Geyser lured their friend Payton Leutner into a forest and stabbed her 19 times in an attempt to appease fictional internet horror character Slender Man.

Weier and Geyser were committed to mental health institutions for, respectively, 25 years to life and 40 years to life.

Dr ian Smith, Cambridge

QUESTION Was the dollar once used as a currency in Britain?

IN A sense, yes. Throughout George III’s reign, Britain suffered from a shortage of coinage. In 1797, this currency crisis was acute as the cost of fighting the French escalated and people began hoarding money, fearing invasion.

One consequence was the introduction of paper money in the form of the £1 note. Another was the Bank of england’s decision to issue altered foreign coins from its reserves.

half a million pounds worth of Spanish dollars, known as eight reale pieces — the pieces of eight of pirate lore — issued by Charles IV of Spain had been stored in British banks as bullion.

They were over-stamped with a small engraving of George III. These coins were valued at four shillings and nine pence, bringing comments such as ‘Two kings’ heads are not worth a crown’ (five shillings) and the insult: ‘The head of a fool stamped on the neck of an ass.’

Between 1804 and 1811, the Bank of england used Matthew Boulton and James Watt’s steam press to erase the design on the dollar and replace it with British emblems and the value, by then raised to five shillings.

The Spanish dollar was legal tender in some British colonies. In 1792, the newly independent United States chose the dollar as its currency.

IS THERE a question to which you want to know the answer? Or do you know the answer to a question here? Write to: Charles Legge, Answers To Correspondents, Daily Mail, 9 Derry Street, London W8 5HY; or email charles.legge@dailymail.co.uk. A selection is published, but we’re unable to enter into individual correspondence.