I am having trouble trying to get the following to work. It will pass the radius, but not the height. Any help you can be would be greately appreciated,

<html>
<head>
<script>


function Cylinder(radius) {


this.radius = radius;
this.volume = volume;

this.surface_area = surface_area;
//this.height = height;

alert("radius1: " + this.radius);
// alert("radius: " + radius);

}



function Cylheight(height){
this.height = height;

//return height;

// alert("hight: " + this.height);
}





function volume() {


var volume = Math.PI * (this.radius * this.radius) * this.height;
alert("radius1: " + this.radius);
alert("hight1: " + this.height);
return volume;



}




function surface_area() {

var surface_area = (Math.PI * 2) * (this.radius * this.radius) + (Math.PI * 2) * this.radius * this.height ;

alert("radius2: " + this.radius);
return surface_area;


}


</script>

</head>

<body>

<h1>Volume, and Surface Area</h1>

<script>



var rad = parseInt(prompt("Enter the radius of the cylinder: "));
var hgt = parseInt(prompt("Enter the height of the cylinder: "));
var myCylinder = new Cylinder(rad);
var myCylheight = new Cylheight(hgt);
alert("The cylinder's volume is " + myCylinder.volume() + " units");
alert("The cylinder's Surface Area is " + myCylinder.surface_area() + " units");
</script>
</body>
</html>