The purpose of this study is to find out the relation between the magnitude of load in one hand and the magnitude of principal strains and maximum shear shear strain on the other hand. The specimen was made of aluminum which has 16.5" length, 1.5" width and 0.25" thickness. A three-element strain gage rosette installed 15,25" from its free end was used as a sensing device. Eight different magnitudes of death load ranging from 1 pound up to 25 pounds were applied 0,25" from the free end, and the magnitudes of strains were then measured using VISHAY strain indicator. The result shows that there are linear relations between the magnitude of load in one hand and the magnitude of principal strainss, and maximum shear strain in the other hand showing that the instrumentation system responded linearly to the change of load magnitude.