Except in a period of emergency determined by an officer of the Fire
or Police Department, or in compliance with the directions of a police
officer or traffic-control sign or signal, when any vehicle shall
be parked in any parking space alongside or next to which a parking
meter is located, the operator of such vehicle shall, upon entering
said parking meter space, immediately deposit or cause to be deposited
in said meter such proper coin of the United States as is required
for such parking meter and as is designated by proper directions on
the meter, and, when required by the directions on the meter, the
operator of such vehicle, after the deposit of the proper coin or
coins, shall also set in operation the timing mechanism on such meter
in accordance with directions properly appearing thereon, and failure
to deposit such proper coin, and to set the timing mechanism in operation
when so required, shall constitute a violation of this article.