Editing Photometer (section)

===Rumford's photometer===
[[File:Rumfords Photometer.jpg|thumbnail|Rumford's photometer]]
Rumford's photometer (also called a shadow photometer) depended on the principle that a brighter light would cast a deeper shadow. The two lights to be compared were used to cast a shadow onto paper. If the shadows were of the same depth, the difference in distance of the lights would indicate the difference in intensity (e.g. a light twice as far would be four times the intensity).