Canon AT 1 - Manual (Page 25)

Loading the Battery
The camera will function only when the
battery is loaded and the main switch is turn­
ed on. Use a silver oxide battery for the power
source. The battery chamber cover can be
opened more easily by using the viewfinder
cover that is inserted into the accessory shoe.
Be careful to load the battery correctly
with the
"+"
side up following the diagram on
the inside of the battery chamber. If the bat­
tery is incorrectly loaded so the polarities are
facing the wrong direction, the camera will
not function. Load the battery by inserting
the " contact first while holding down the
battery in the bottom of the battery chamber.
When loading or removing the battery, make
certain that the main switch is set at OFF.
■ Only a silver oxide battery can be used
and other types cannot be used. In general
use, the battery will last one year. Safety
circuitry is built in the camera to keep the
shutter from being released when the voltage
of the battery becomes insufficient.