【正文】
ity departments, which can help public security officers work out the ages and heights of suspects according to the pressing shapes and lengths of the footprints they leave. With its special way of calculating, its accuration in calculation and its function of working out the ages and heights of suspects, the ruler takes the lead in the world. The ruler is solely invented in China and enjoys the advantages of easy usage, precise calculation and convenient carriage. The Invention and Implication Of Footprints Measurement Ruler After 18 times of improvements, the sales volume of the ruler reaches 100,000 in China, and it is playing important roles in fighting against crimes and keeping a good and safe social environment. It was granted of China’s national patent right after a fur