Abstract: A roller clip having three prongs is disclosed. It comprises a u-shaped member as a first leg terminating in a first longitudinal member and a second leg terminating in a second longitudinal member. The first and second longitudinal members are parallel and the first and second legs are interconnected by an interconnecting portion. A third longitudinal member projects from the interconnecting portion and is substantially parallel to the first and second longitudinal members. The third longitudinal member terminates in an upturned end. A handle also projects from the interconnecting portion and is generally located in the plane of the u-shaped member. Preferably, the handle and the third longitudinal member are integral and form an obtuse angle therebetween. The first and second longitudinal members may be flat and a notch for latching is provided between the first leg and the first longitudinal member and between the second leg and the second longitudinal member.

Abstract: A method and device for determining acentricities in a powder material by illuminating the powder with a collimated coherent light beam of given wave-length which generates a second harmonic in the material. The second harmonic with the fundamental removed by filters is divided by a beam splitter and sent to two photomultipliers -- one of which has a narrow band filter to select only light of one wave-length. If all the light is generated at the second harmonic equal signals are produced by the photomultipliers. If non-second harmonic radiation is produced, a larger signal will be produced in the unfiltered reference channel.