Single crystals have become vitally important to many areas of research in metallurgy, engineering, physics and chemistry. With the introduction of theories about dislocations and their movement during plastic deformation of metals came a need for single crystals to test these theories. The fact that theoretical yield strengths are almost 1000 times higher than those normally observed needs to be explained to satisfy the curiosity of the metallurgist. The explanation may also have very practical applications. It is interesting to note that whiskers, metallic single crystals in tiny hair-like shape, do have strengths approaching the theoretical. Dr. Halden (13), manager of ceramics research at Stanford Research Institute, reports that techniques are being developed to use this strength in composites and self-bonded structures.