I have tried to improve telescopes and practiced continually to see with them. These instruments have play'd me so many tricks that I have at last found them out in many of their humours.
~Sir William Herschel
Spyglasses today, a.k.a. monoculars! ("Monoculars" sounds like a funny word, although "binoculars" is ordinary. Is it like "disgruntled" and "gruntled"? "Rejected" and "jected"? I'm just making stuff up now.)
Priscilla Long writes, "The spyglass was the first scientific instrument to amplify the human senses, to make previously invisible objects visible." Read the whole article (about Galileo and the spyglass) here.
Galilean spyglass, reproduction of one of Galileo's spyglasses, XX.
photo by Alessandro Nassiri, Museo scienza e tecnologia Milano
Nachet collection: two spy glasses made by Dolland, London
Exhibit in the Mathematisch-Physikalischer Salon (Zwinger), Dresden, Germany
O catalexo-Looking at the sea. The spyglass.
photo by luscofusco
Opera glasses, exhibit in the Brooklyn Museum
photo by Daderot