Industrial revolution

1. INDUSTRIAL REVOLUTION (CAMERA, STEEL)
The history of the camera can be traced much further back than the introduction of
photography. Cameras evolved from the camera obscura, and continued to change through
many generations of photographic technology, including daguerreotypes, calotypes, dry
plates, film, and digital cameras.
Photographic cameras were a development of the
camera obscura which uses a pinhole or lens to project
an image of the scene outside upside-down onto a
viewing surface.
Daguerre coated a copper plate with silver, then
treated it with iodine vapour to make it sensitive to
light. The image was developed by mercury vapour and
fixed with a strong solution of ordinary salt (sodium
chloride). Henry Fox Talbot perfected a different
process, the
collotype, in 1840. Both used cameras that were little
different from Zahn's model, with a sensitized plate or
sheet of paper placed in front of the viewing screen to
record the image. Focusing was generally via sliding
boxes. Film allowed the movie camera to develop from an
expensive toy to a practical commercial tool. Now a days,
digital cameras now include wireless communication
capabilities (for example Wi-Fi or Bluetooth) to transfer,
print or share photos, and are commonly found on mobile
phones.
The history of the modern steel industry began in the late 1850s, but since then steel has
been basic to the world's industrial economy. Previously steel was very expensive to
produce and only used in small expensive items such as knives, swords and armour.
However the global steel industry has been going
through major changes since 1970. China has
emerged as a major producer and consumer, as has
India to a lesser extent. Consolidation has been rapid
in Europe.
Eads Bridge across the Mississippi River, opened in
1874 using Carnegie steel.