timers

I created the following function and calling it like this but the problem is i have to keep hitting the start button for the text area to change seconds.  I want to be able to click on start and it will count automatically but it isn't working now. Why is that?

      $("#btn1Start").click(function() {                  
            timer1 = setInterval($.do_time('hr1','min1','sec1'), 1000);
        });
      
      $("#btn2Start").click(function() {                  
            timer2 = setInterval($.do_time('hr2','min2','sec2'), 1000);
        });

      $("#btn3Start").click(function() {                  
            timer3 = setInterval($.do_time('hr3','min3','sec3'), 1000);
        });

//Timer JQuery function

(function($) 
{
	$.do_time = function(hrName,minName,secNam) {

		// parseInt() doesn't work here...
				hour = parseFloat($("#"+hrName).text());
				minute = parseFloat($("#"+minName).text());
				second = parseFloat($("#"+secNam).text());
				second++;
				
				
				
				if(second > 59) {
					second = 0;
					minute = minute + 1;
				}
				if(minute > 59) {
					minute = 0;
					hour = hour + 1;
				}
				
				$("#"+hrName).html("0".substring(hour >= 10) + hour);
				$("#"+minName).html("0".substring(minute >= 10) + minute);
				$("#"+secNam).html("0".substring(second >= 10) + second);
		
			
			}//End Doo time function
})(jQuery);

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