What鈥檚 that in Brooklyn bridges?
SEVERAL readers have commented on a phrase used in various publications to describe James Cameron鈥檚 journey into the Mariana trench. Robert Moore, for example, saw the phrase in by Seth Borenstein of Associated Press, which said of the dive: 鈥淚t鈥檚 a mission to the deepest part of the ocean, so deep that the pressure is the equivalent of three SUVs sitting on your toe.鈥�
Steve Morris saw the same phrase in an on the dive. He comments: 鈥淚f that was elephants, I could understand it, because we use the unit all the time. But SUVs? This must be an American unit.鈥�
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Yet other readers encountered a different unit to describe the trench. An article anticipating the dive in the UK鈥檚 Daily Telegraph on stated that the pressure in the trench is 鈥渆quivalent to 8000 elephants all standing on a Mini Cooper鈥�.
Doug Cross was not happy about this, despite the familiarity of elephants and the Englishness of the Mini Cooper car. He points out: 鈥淭here鈥檚 only room for a single elephant to stand on the roof of a Mini, or indeed, on the back of another elephant. So they must all be in a single stack, 8000 elephants high. The average adult male African elephant stands around 3.5 metres at the shoulder, so the stack would be 28 kilometres high.鈥�
At this point, enter the BBC with an entirely new unit of pressure to confound all the others. Describing not the Mariana trench but the fossil of a huge snake named Titanoboa, tells us, as Feedback readers were quick to notice, that this monstrous snake 鈥渃rushed its prey with the constricting force of 400 pounds per square inch 鈥� the equivalent of lying under the weight of one-and-a-half-times the Brooklyn bridge鈥�.
On the thorough wrapping of Penny Pengryffyn鈥檚 packet of Jindi Brie cheese is the message 鈥淐onsume after opening鈥�. Sage advice, says husband Marc. Ignore it at your digestive peril.
Butterflies help us to breathe
READER Jonathan Worton recently picked up a leaflet advertising the Wye Valley Butterfly Zoo, which is situated near Symonds Yat, a beauty spot on the border between England and Wales. People running a butterfly zoo must doubtless know a thing or two about butterflies, so the revelation that follows makes Feedback appreciate that we barely understood the importance of these beautiful insects.
鈥淏utterflies,鈥� the leaflet informed Jonathan, 鈥渁re among the largest collection of creatures in the animal kingdom and help to provide one-third of the oxygen we breathe.鈥�
FEEDBACK鈥橲 comments on the Lyons Electronic Office (LEO I) computer (24 March) have prompted many readers to write 鈥� particularly about our doubt that 0.5 megahertz was a likely clock speed for a computer in 1951.
The reader who made us most proud of the reach of Feedback was Mark Shuttleworth, who writes: 鈥淚n the late 1970s I was privileged to have been a computer operator on an LEO III鈥� It was an awesome machine that I remember with great fondness. On final decommissioning 鈥� in 1978, I think 鈥� I was allowed to keep a souvenir: the engineer鈥檚 copy of the 鈥楲EO III Users鈥� Manual, Volume 1, Computer Facilities鈥�.鈥�
So we have the original source data 鈥� albeit for a slightly later model. Mark describes the work as 鈥渁 far cry from anything we鈥檇 call a users鈥� manual today. It describes in great detail the innermost workings of this astonishing piece of engineering鈥�, including the time taken for each logical operation.
Of these, a HALT instruction took a mere 20 microseconds. Dividing 1 second by this shortest operation time gives us the nearest equivalent to what we would nowadays understand as clock speed: 0.05 megahertz.
However, as Mark concludes, this underestimates the machine鈥檚 powers: it could 鈥減erform operations on pound, shilling and pence amounts in a single computer instruction鈥�. For readers who did not go shopping in the UK before 1971, we should explain that this was an impressive feat of mixed-base arithmetic: there were 20 shillings to the pound and 12 pence to the shilling.
Crouch down for optimum effect
鈥淪OME product instructions,鈥� Stephen Battersby observes, 鈥渟eem to be asking you to bend over backwards 鈥� or at least crouch down.鈥�
He gives the carbon monoxide alarm bought by a colleague as an example. In section 3 of the manual (鈥淚nstallation Locations鈥�) comes the advice: 鈥淧lacing the alarm at eye level allows for optimum monitoring of the display鈥�.
Three pages later, section 4 (鈥淚nstallation Instructions鈥�) declares: 鈥淏e sure the alarm is no more than three feet from the floor鈥�.
FINALLY, the citronella mosquito-repellent armbands Mary Voice bought at a pharmacy in Melbourne, Australia, had a sobering warning on the box. It said: 鈥淚f a burning sensation or irritation occurs, please take off your skin immediately.鈥�
Mary says she would rather take off the armbands.