I would suggest to follow below steps:
1) call startTimer( ) in each of the page where you want to show the elapsed timer.
2) In the Tick method pass the span id where you want to show the elapsed time.
So each time you call tick it will show the elapsed time in the given span id.
That span can be in any page and inside any DIV.
Below is the code for tick method.
function tick(spanId )
{
++seconds;
var secs = seconds;
var hrs = Math.floor( secs / 3600 );
secs %= 3600;
var mns = Math.floor( secs / 60 );
secs %= 60;
var pretty = ( hrs < 10 ? "0" : "" ) + hrs
+ ":" + ( mns < 10 ? "0" : "" ) + mns
+ ":" + ( secs < 10 ? "0" : "" ) + secs;
document.getElementById(spanId).innerHTML = pretty;
}
Hope it helped.