Very small objects

The Collier classification system for very small objects is beautiful and can be found here.

Sea Forts

A set of photographs of these things on the north kent coast is on flickr here and the photographer has written a brief history of them here.

Humboldt's Parrot

In 1804, the Prussian naturalist and explorer Alexander von Humboldt returned from his five-year expedition to Central and South America, bringing with him a transcription of 40 words spoken by a parrot which was believed to be the last speaker of an extinct language.

In 1997 Rachel Berwick taught these 40 words to two amazonian parrots, exhibiting them behind translucent screens as last traces of a lost world. She has subsequently used recordings of these parrots to teach other parrots. There are now a total of six speakers of Humboldt's 40 words. More on this and some very cool other projects on Rachel Berwick's website here, and brought together with similar themes at language week at the Kircher Society here.

Sound mirrors

Acoustic mirrors built on the south and northeast coasts of England between about 1916 and the 1930s. Some beautiful pictures on flickr here and here.