INDEX 305 number: artificial, 85; co-prime, 173; constructible, 78; irrational, 175­77, 185, 223; transcendental, 79 d'Oresme, Nicole, 259 origami, 110, 125 Oughtred, William, 227, 234­36, 240, 251­54 pantograph, 51 parabola, 13, 43­45, 127, 134 parallel postulate, 70 parallelogram: area of, 142 Pascal, 107 Peaucellier, Charles Nicolas, 34, 60 pendulum, 66 pentagon, 98, 212 perimeter, 194 , 72, 79­80, 92, 238­39 planimeter, 149­70; Goodmans, Sangwin, Guy William Farrier, 246 Sarrus, Pierre Frédéric, 33 scale: circular, 240; double, 85; folded, 237; logarithmic, 85, 231; of decimals, 84; specially designed, 241; Vernier, 81­83, 116, 153, 162, 188, 267 Scott Russell, 39 sector, 84­87 series: arithmetic, 113, 247; geometric, 122; harmonic, 259­61 slide rule, 227­49; bespoke, 241; circular, 240­41; invention of, 233­37, 251; logarithmic, 229­33, 237­40; non-logarithmic, 247 snowflake, Koch's, 146 standard: British, 16, 206­10; International paper, 177; length, 66­69, 180­82 Stone, Edmund, 235