Lab equipment mystery device...

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My physics teacher found some devices that measure the period/frequency of an object on a spring. The centripetal force is measured in Newtons with a spring scale, then the known mass is spun around it's string, where someone is applying a constant force by twisting the post below. (The mass then spins around its post, stretching the spring mor eor less depending on the centripetal force on it. A stopwatch can be used to measure the period). This force is only what's needed to make the bottom of the mass align with the post (refer to this diagram): http://img433.imageshack.us/my.php?image=mysterydeviceka3.png The point of this query is our teacher only found these and they're basically antiques. He's trying to find a good name for them, and I'm trying to find the original name. Does anyone remember this lab equipment and what its "actual" name is?