|
Showing 1 - 25 of
261 matches in All Departments
Unlike some other reproductions of classic texts (1) We have not
used OCR(Optical Character Recognition), as this leads to bad
quality books with introduced typos. (2) In books where there are
images such as portraits, maps, sketches etc We have endeavoured to
keep the quality of these images, so they represent accurately the
original artefact. Although occasionally there may be certain
imperfections with these old texts, we feel they deserve to be made
available for future generations to enjoy.
This historic book may have numerous typos and missing text.
Purchasers can usually download a free scanned copy of the original
book (without typos) from the publisher. Not indexed. Not
illustrated. 1898 edition. Excerpt: ...as a presentation of what
was taking place at the time, but as a re-production of some
previous performance. This wonderful result has virtually been
attained by the application of delicate and ingenious machinery
designed to make the phonograph and the camera work synchronously.
The first part of the problem was the production of a succession of
so-called instantaneous photographs at an extremely rapid rate. In
the actual apparatus forty-six photographs are taken every second,
a feat which wo'ild beforehand be thought impracticable. This is
accomplished by making use of a band of sensitive celluloid film,
which alone admits of being moved and stopped with the desired
rapidity. The movement is imparted by an electric motor, and the
arrangement is such that for each exposure the film is held
stationary for 9ffths of th of a second, during which the lens is
uncovered, then for the remaining 1'0th it is covered, while at the
same time the film is jerked forward so as to expose a fresh
surface to receive a new impression. Obviously the mass moved and
stopped with this rapidity (which without the stoppages is at the
rate of 26 m1les an hour) must be small, and it is found that
photographs about I in. in diameter cannot be much exceeded in view
of this condition. The lens has to be entirely stopped or screened
during the tenth of the short interval (jiith of a second) in which
the onward movement of the film is taking place, and it has to be
practically open during the remaining fyths of the interval (joths
of one second) in which the film is held stationary in order to
receive the photographic image. These alternations of movement and
stoppage must take place with the utmost regularity, and Edison has
used a beautifully regulated electro-motor...
This pioneering work was the first documented survey of a system
that helped fugitive slaves escape from areas in the antebellum
South to regions as far north as Canada. Comprising fifty years of
research, the text includes interviews and excerpts from diaries,
letters, biographies, memoirs, speeches, and other firsthand
accounts.
|
You may like...
Captain America
Jack Kirby, Joe Simon, …
Paperback
R610
R476
Discovery Miles 4 760
|