File:Didcot disc and crossbar signal.jpg

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Summary

Description	English: A Great Western Railway disc and crossbar signal at Didcot Railway Centre, England. This early form of mechanical signal was rotated to show one of two aspects to on coming trains. The disc represents 'all right' and the the crossbar represents 'stop'. On this one the extended tails on the crossbar were a later modification to identify signals protecting the down line (the one travelling away from London).
Date	24 May 2009
Source	Own work
Author	Geof Sheppard

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File usage

The following pages on Schools Wikipedia link to this image (list may be incomplete):

Great Western Railway

Metadata

This file contains additional information, probably added from the digital camera or scanner used to create or digitize it. If the file has been modified from its original state, some details may not fully reflect the modified file.

Camera manufacturer	Canon
Camera model	Canon PowerShot G7
Exposure time	1/160 sec (0.00625)
F-number	f/8
Date and time of data generation	12:19, 24 May 2009
Lens focal length	14.783 mm
Orientation	Normal
File change date and time	12:19, 24 May 2009
Y and C positioning	Centered
Exif version	2.2
Date and time of digitizing	12:19, 24 May 2009
Image compression mode	3
Shutter speed	7.3125
APEX aperture	6
Exposure bias	0
Maximum land aperture	3.34375 APEX (f/3.19)
Metering mode	Pattern
Flash	Flash did not fire, compulsory flash suppression
Colour space	sRGB
Focal plane X resolution	12,710.801393728
Focal plane Y resolution	12,725.581395349
Focal plane resolution unit	inches
Sensing method	One-chip colour area sensor
Custom image processing	Normal process
Exposure mode	Auto exposure
White balance	Auto white balance
Digital zoom ratio	1
Scene capture type	Standard

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