Use of a Photocopied Slide Rule to Complement Limited Function Calculators Decreased cost and increased power of the new scientific calculators have made the slide rule virtually obsolete. However, the slide rule does have its advantages. There is less of a security problem (few want what they cannot use), and the slide rule provides (and demands) practice reading assorted scale divisions. Even with the low cost ($20-40) many students cannot afford calculators necessary to solve logarithms, square roots, and cube roots as encountered in pH and equilibrium problems. Photocopying the K, A, D, and L scales of the fixed part of aslide rule provides a very inexpensiveand convenient device that will give thestudent the capability to find log$ squares, and cuhes and their roots. This coupled with a simple four function calculator is as powerful as is required for most college chemistry problems. A hairline or straight edge can be made from a piece (2 X 4 cm) of cellulose acetate or suitahle transparent plastic. A 3 cm vertical slit is made in the center and slid over the scales. The complete slide rule can he made by photocopying the sliding scale separately, trimming along the top and bottom edges, and cutting a slit a t each end of the fixed body to hold the sliding scale. There is no copyright prohlem because the scales on the slide rule are based on logarithms and are universal. In this way students are provided with a useful calculating tool and practice in reading logarithmic and other scale divisions. Also, the tradition is kept alive for a mechanical calculator-one that does not require batteries or recharging. Paul M. Barelski LeMoyne-Owen College 807 Walker Avenue
Memphis, TN 38126
718
Journal of Chemical Education
