The Collaborative International Dictionary
Dynactinometer
Dynactinometer \Dy*nac`ti*nom"e*ter\, n. [Gr. ? power + E. actinometer.] An instrument for measuring the intensity of the photogenic (light-producing) rays, and computing the power of object glasses.
Wiktionary
dynactinometer
n. An instrument for measure the intensity of photogenic rays and computing the power of object glasses.