Cornus Apparatus is used to conduct experiments for determining Poisson's ratio and Young's Modulus for a range of materials such as Perspex, glass, etc. Weights are precisely positioned at both ends of the bar so that it bends longitudinally downward. With a glass plate on the bar, it produces interference pattern that is studied to determine the extent of longitudinal and lateral bending. Hence, Poisson ratio and Young's modulus can be deduced. As light sources, Sodium vapor lamp and spectral LED's are utilized. Precision micrometer with durable traveling microscope is used for precise measurements.