| GENERAL CHARACTERISTICS ITEM DESCRIPTION | PLASTIC W/SQUARE BASE; BASE SCALE GRADUATED IN LOGARITHMS TO BASE 10 OF NUMBERS 0.5 TO 1000; ELEVATION SCALE DIFFERENCE ON THE DISC SHALL BE GRADUATED IN LOGARITHMS TO BASE 10,OF ONE HALF THE SINE OF TWICE THE ANGLES FROM 3 MINUTES TO 45 DEGREES; HORIZONTAL DISTANCE SCALE ON THE DISC SHALL BE GRADUATED TO THE LOGARITHMS BASE 10,OF THE COSINE SQUARED OF THE ANGLES FROM 0 TO 45 DEGREES |