Photometer, after Wheatstone

Londen Elliott Brothers, circa 1860

How to compare the intensities of two light sources? For this, Charles Wheatstone (1802-1875) invented this smart photometer around 1843. The apparatus contains a mechanical device which drives around a shiny steel bead along the same elegantly curving path. A source of light reflecting in the bead causes a continuous trace on the retina because of the persistence of vision. A second source of light has the same effect, but on an other spot in the eye. By altering the position of one of the light sources, the figures in the eye can be adjusted till they have exactly the same brightness. If the distances to the photometer are known, the intensity of one light source compared to the other can be calculated.

Administration name

Fysisch Kabinet

Title

Photometer, after Wheatstone

Translated title

Photometer, after Wheatstone

Creator

[{'date_of_birth': u'', 'role': u'', 'qualifier': '', 'date_of_death': u'', 'creator': 'Elliott Brothers, Londen'}]

Object category

03.06

Dating

[{'start': '1860', 'end_precision': u'', 'end': u'', 'start_precision': 'circa'}]

Material

[{'material': 'brass'}, {'material': 'Cork'}, {'material': 'Glass'}]

Measurements

[{'notes': u'', 'part': 'geheel', 'type': 'diameter', 'value': '54', 'unit': 'mm'}, {'notes': u'', 'part': 'geheel', 'type': 'hoogte', 'value': '26', 'unit': 'mm'}]

Object number

FK 0300

Inscription

[{'content': 'Elliot Bros 30, Strand, London', 'type': 'signatuur'}, {'content': 'ELLIOTT BROTHERS OPTICIANS STRAND LONDON', 'type': 'signatuur'}]

Reproduction reference

[{'reference': '..\\images\\Fysisch\\Gekoppelde afbeeldingen\\FK 0300.jpg'}]