// Get bubble chart area
var chartArea = bubbleChart.getChartArea();
// Determine label parameters
var settings = {
    Length: 15, // Label length
    Chart: bubbleChart,
    Stroke: PP.Color.Colors.black, // Black label color
    Thickness: 2 // Label width in pixels
};
// get vertical axis level lines for the X axis
var xItems = chartArea.getGrid().getVerticals()._Items;
for (var i in xItems) {
    // Create a new axis label
    var marker = new PP.Ui.ChartMarker(settings);
    // Set a new value for axis label
    var value = xItems[i].getValue();
    marker.setValue(value);
    // Render label
    var secondCoord = bubbleChart.getChartArea().getPaperArea();
    marker.draw(bubbleChart.getChartArea()._GridLayer, PP.Ui.VisualType.X, secondCoord);
};
// Get horizontal level lines for the Y axis
var yItems = chartArea.getGrid().getHorizontals()._Items;
for (var i in yItems) {
    // Create a new axis label
    var marker = new PP.Ui.ChartMarker(settings);
    // Set a new value for axis label
    var value = yItems[i].getValue();
    marker.setValue(value);
    // Render label
    marker.draw(bubbleChart.getChartArea()._GridLayer, PP.Ui.VisualType.Y, 0)
};