The mechanical cow is unique in many ways. It enables people track time just like One O'clock Gun.

The cow releases a cloud of white smoke throughout the day in the historic city of Edinburgh informing people time in a funny way.
The mechanical cow is found in the Edinburgh's historic Old Town. The backside of the cow is tied to the side of a Rowan Tree pub.
The beast simply lifts its tail and releases white smoke at passers-by throughout the day. The cow breaks wind twice in a day, 1100 GMT and 1300 GMT. In this way, it helps people know time.
The flatulent cow was installed earlier this year. It is now one of the attractive points for the tourists visiting the city.
Via: BBC