Comprising 9mm square brass beam, one meter long approx., which is supported horizontally on two knife edges fixed on cast iron G-clamps. A hanger for loading, and two adjustable plane mirrors with mounts are provided which are clamped on to the beam. On applying load the deflection in the beam causes the image of the plane mirror to shift. This deflection is measured using a reading telescope which makes the results very accurate. Supplied without slotted weight set.