Sun as a source of heat, [272]

Surface, relation of, to movability, [193]

Syphon, [172]

Tantalus, cup of, [174]

Telegraph, [415]

Telescopes, [350]

Tenacity, [25]

Tenacity, comparative, of substances, [26]

Tenacious substances, value of, [27]

Thermometer, [37], [276]