Mr. Defty has sought in the latter to apply the principle of heating the air and gas in a simple manner, with the object of obtaining improved photometrical results.    From Wordnik.com.  [Scientific American Supplement, No. 362, December 9, 1882] Reference

The ratio of the radiant flux with the wavelength Lambda (m) and the radiant flux with the wavelength Lambda both radiations causing the same brightness impression in certain photometrical conditions.    From Wordnik.com.  [2. Elements] Reference

Letheby photometer, in order to give your readers an opportunity of estimating for themselves the effect which such variations from the true distance between the standard light and that to be measured, as shown in this series of photographs, must exercise on photometrical observations made by the aid of either of the instruments named.    From Wordnik.com.  [Scientific American Supplement, No. 484, April 11, 1885] Reference

Opposite this table we installed, later on, our photometrical chamber, which was constructed on the Bunsen principle.    From Wordnik.com.  [Edison, His Life and Inventions] Reference

In carrying out a series of photometrical experiments lately, I found that it was a matter of considerable difficulty to keep the flames of the standard candles always at their proper distance from the light to be measured, because the wick was continually changing its position (of course carrying the flame with it), and thus practically lengthening or shortening the scale of the photometer, according as the flame was carried nearer to or farther from the light at the other end of the scale.    From Wordnik.com.  [Scientific American Supplement, No. 484, April 11, 1885] Reference

Stine, W M, photometrical measurements.    From Wordnik.com.  [The Dancing Mouse A Study in Animal Behavior] Reference