function drawTideGraph( dt ){ 
	
	var dataCm = [];
	var dataZo = [];
	for (var i = 0; i < 25; i++){
		dataCm.push([i, dt[i].cm]);
		dataZo.push([i, zo]);
	}	
	
	var plot = $.plot($("#placeholder"),
    		    [
    		        {
    		            label: "平均水面(Zo)",
    		            color: 2,
    		            data: dataZo
    		        },
    		        {
    		            label: "水面の高さ",
    		            color: 1,
    		            data: dataCm,
    		            lines: {show: true },
    		            points: { show: true }
    		            
    		        }
    		    ]
    		    ,{
    		        legend: {
    		            show: true,
    		            noColumns: 2,
    		            container: $("#legend")
    		        },
    		        yaxis: { min: minRatio,	max: maxRatio },
    		        selection: { mode: "xy" },
    		        grid: { hoverable: true, clickable: false }
    		    }
    		);

    function showTooltip(x, y, contents) {
        $('<div id="tooltip">' + contents + '</div>').css( {
            position: 'absolute',
            display: 'none',
            top: y + 5,
            left: x + 5,
            border: '0px solid #ffffff',
            padding: '2px',
            'background-color': '#ffffff',
            opacity: 0.80
        }).appendTo("body").fadeIn(200);
    }

    var previousPoint = null;
    $("#placeholder").bind("plothover", function (event, pos, item) {
        //$("#x").text(pos.x.toFixed(2));
        //$("#y").text(pos.y.toFixed(2));

        if (item) {
        	if (item.seriesIndex == 1){
	        	if (previousPoint != item.datapoint) {
	                previousPoint = item.datapoint;
	                    
	                $("#tooltip").remove();
	                var x = item.datapoint[0].toFixed(2),
	                    y = item.datapoint[1].toFixed(2);
	                    
	                showTooltip(item.pageX, item.pageY, x + "時：" + y + "cm");
	            }
        	}
        }else {
            $("#tooltip").remove();
            previousPoint = null;            
        }
    });
}