• Webster's Revised Unabridged Dictionary
    • n Tithonometer An instrument or apparatus for measuring or detecting tithonicity; an actinometer.
    • ***
Century Dictionary and Cyclopedia
    • n tithonometer An instrument devised by Dr. John W. Draper (1844) to measure the tithonic or chemical action of light-rays by their effect in causing the chemical union of chlorin and hydrogen. See the quotation.
    • ***
Chambers's Twentieth Century Dictionary
    • n Tithonometer an instrument for measuring the tithonicity of light-rays
    • ***


Webster's Revised Unabridged Dictionary
Tithon,ic + -meter,