993.1002.1: Hazen's Kratometer, 1910-1944

Additional Images

993.1002.1: Hazen's Kratometer.
Image No. 3438 ; Photographer: Helen Kingsley

Object Description

HAZEN's Kratometer [also known as Keratometer or ophthalometer]. A cased instrument consisting of a stand with a set screw table clamp to which a head, with a battery guide and eye cup, is slotted into and held in place by a set screw, with the convergence rod. A card carrier, holding a printed card [Jaeger standard] with writing on one side and a vertical line on the other, slides along the convergence rod which has a graduation scale of 10cm -37cm. The two 'Batteries' each have fifteen prism lenses; one battery contains prisms with strength graduating from 1 degree to 15, by degree intervals, and the second contains prisms graduating from ¼ degree to 3¾ degrees. A lens disc, containing five round lenses, is connected to the phorometer slide and a eye cup. A Maddox plate [consisting of a Maddox Rod and a Maddox double prism] and a red glass lens slide into the phorometer slide which in turn slides into the head. On the head, behind the battery slide, in front of the phorometer slide, is a large slot in which can be placed an extra square prism lens of which there are four. There are three spare battery prism lenses, a spherical clear convex glass lens mounted in metal rim with handle and two large concave lenses. Case dimensions given.

Object Classification

Accession Number: 993.1002.1
Collection: Ophthalmology
Date: 1910-1944

Object Dimensions

  • Height: 9 cm
  • Width: 43 cm
  • Depth: 15 cm

Object Parts

  • a) Lined hinged case
  • b) Clamp stand
  • c) Head with stem, battery guide and eye cup
  • d) Phorometer slide with lens disc, lenses and eye cup
  • e) Battery [lenses]
  • f) Battery [lenses]
  • g) Maddox plate
  • h) Red glass
  • i) Convergence rod
  • j) Printed card
  • k) Card holder
  • l) Spare battery prism lens
  • m) Spare battery prism lens
  • n) Spare battery prism lens
  • o) Square prism lens
  • p) Square prism lens
  • q) Square prism lens
  • r) Square prism lens
  • s) Concave lens
  • t) Concave lens
  • u) Convex trial lens

Object Materials

  • blued steel,
  • card,
  • cast iron,
  • chrome plate,
  • copper alloy,
  • enameled paint,
  • glass,
  • leather,
  • metal,
  • plastic,
  • printing ink,
  • steel,
  • textile,
  • unidentified coating,
  • velvet,
  • wood

Acquisition Detail

  • Owner: F. R. Wheatley
  • History of Use: For gymnastic treatment of the extrinsic muscles of the eye.