INDEX 



365 



Printing, directions for, 320, 322 



Prism, 304 



Procyon, 34, 41 



Proton, 165; size of, 165 



Pulley, 346 



Pulleys, law of, 347 



Pumice, 64, 66, 67 



Pump, 127, 128; air, 144; force, 128; 



lift, 127, 129; making, 128 

 Pupil of eye, 303 

 Pyramid of Cheops, 16 

 Pyrite, 48, 50, 62 

 Pyrolusite, 50 

 Pyroxene, 50, 58, 6 1, 65; characteristics 



of, 58, 61 



Quartz, 44, 45, 47, 51, 53, 62; character- 

 istics of, 52, 62; rose, 54; smoky, 54; 

 solution of, 53; veins, 52 



Quartzite, 51, 74 



Radiator, 194 



Radio-active substances, discovery of, 

 173 



Radio: broadcasting, 251, 252, 254, 278; 

 frequency, 255, 268, 274; nature of, 

 250; receiving, 251, 256, 265; tele- 

 phone, 274, 276; transmitting station, 

 251,252,254; tuning coil, 260; waves: 

 continuous, 267, 275, speed of, 255; 

 wave-trains, 255 



Radium, 5, 171, 173, 174 



Radium paint, 174 



Railroad, 189, 190 



Rain, 157 



Rainbow, 308 



Ram, the, 35, 36 



Raven, the, 41 



Rays: alpha, 173; beta, 173, gamma, 

 173 



Rectification, 257 



Reducing, directions for, 324 



Redwood, 127 



Reflection, 285, 291; law of, 286, 287; 

 total, 295 



Refraction, 285, 292; amount of, 293; 

 index of, 293; law of, 293, 294 



Regulus, 36 



Relays, 213 



Resistance, 227 



Resonance, 330, 336 



Rhyolite, 66 



Rigel, 31, 40 



Rock, 45, 47 



Rocks : crystalline, 64; formation of, 



62; igneous, 62, 63, 64, 70; igneous, 



table of, 66; metamorphic, 59, 74; 



plutonic, 64; sedimentary, 59, 63, 70; 



volcanic, 64 

 Ruby, 51, 54 

 Rusting, 149 



Sailboat, 118 



Sailboats, American, 118; ancient, 118; 

 records of, 118 



St. Elmo's fire, 35 



Sagittarius, 39 



Salt, 165 



Saltpeter, 50 



Salts: color of, 172; naming of, 177; 

 solubility of, 172 



Sand, formation of, 52; torpedo, 53 



Sandstone, 45, 51, 63, 74; character- 

 istics of, 73 



Santos-Dumont, 88, 94 



Sapphire, 51, 54 



Saturn, 2, 7, n, 13, 39; rings of, 9 



Savery's engine, 179 



Savery's steam pump, 179 



Scale: intervals of, 333, 334; musical, 

 333 



Scales, 340 



Scales, the, 38 



Scandium, discovery of, 173 



Schist, 74 



Schooling, days of, 188 



Scissors, 343 



Scorpion, 38, 39 



Screw, 349; pitch of, 349 



Seasons, change of, 1 1 



Selene, n 



Selenite, 49, 56, 217 



Serpentine, 50, 58, 60, 61; characteris- 

 tics of, 60, 6 1 



Seven Sisters, 30 



Sewing-machine motor, 239 



Shale, 73, 74 



Siderite, 50 



Silica, 65 



