Down the tubes.

Yesterday I was brought up short whilst reading a review of a book about Prato, a city near Florence which we'd stayed in three years ago. Once again I was reading something which seemed to make no sense:

Dei Professori Nesi scrive che «usano il telescopio e non il cannocchiale e così non vedono le persone» [Nesi writes that because academics use a telescope rather than a telescope they don't see individuals.]

I was familiar with the word 'cannocchiale', meaning 'telescope', and its similarity to the English word seemed to suggest that 'telescopio' was a synonym. But then the sentence would be meaningless. Perhaps 'telescopio' was a false friend, analogous to 'libreria' which - contrary to one's natural assumptions - means 'bookshop' not 'library'? So I looked it up in an Italian-English dictionary and found that although the word did indeed mean telescope its use was limited to the type used by astronomers rather than the sort Long John Silver carried in his pocket. That was a cannocchiale! So, as in the case of straps, where English makes do with one word, Italian has several.
  Then I recalled the archaic word 'spyglass' used to denote the seafarer's instrument. Perhaps we, too, once had words to discriminate between an optic looking at the stars and one helping you to spot whether the ship bearing down on you was flying the Jolly Roger? Only up to a point. To my surprise, the OED revealed that 'spyglass' didn't enter the language until 1705 and dropped out after 1875. 'Telescope' which I'd assumed to be the more modern coinage entered the language in the early 17th century - in the Italian or the Latin form - and denoted the astronomer's instrument. The Italians on the other hand - according to the Devoto-Oli dictionary - have been using both 'cannocchiale' and 'telescopio' since the 17th century: Lo Zingarelli says the former entered the language in 1608 and the latter in 1611.
  So in the end I'm none the wiser as to why the Italians have different labels for the two types of telescope while we rely on context to distinguish them. Maybe there's some profound psychological reason, but I'm buggered if I know what it is.