     func intersectionPoint(ray:Ray) -> Vector?
     {
         if let t = intersection(ray) {
-            return ray.atT(t)
+            return ray.t(t)
         }
         return nil
     }

        return Vector()
    }
    
    /**
        Return the time t that the ray first intersects the 
        object, or nil if no hit occurs
    **/
    func intersection (ray:Ray) -> Double?
    {
        return nil

{
    var centre:Vector = Vector(x: 0.0, y: 0.0, z: 0.0)
    var radius:Double = 1.0
    var radiusSquared:Double = 1.0
    
    /** 
        Currently using a geometric solver. 
