Pocket comparator

A pocket comparator is an optical device for measuring and inspection comprising a loupe and a reticle.^[1] The instrument was developed and manufactured by the Bell & Howell Company, but similar instruments of other names are made by other manufacturers.^[2]^[3]

Reticle of Bell & Howell Pocket Comparator

Typographer Henri Friedlaender at work. Note Pocket Comparator at 01:10.

It is used for:

Linear measurements in fractions of an inch^[4]^[5]^[6]
Circular measurements in fractions of an inch
Radius measurements
Angle measurements
Narrow line width measurements^[7]
Circular measurements in decimals of an inch
Linear measurements in inches
Linear measurements in millimeters

Measurements are performed by bringing the surface of the reticle as close as possible to the work inspected.^[8]

References[edit]

^ "The Pocket Comparator - A New Optical Measuring Instrument". in: Electrical Engineering (Volume 69, Issue 3, p. 220) March 1950 http://ieeexplore.ieee.org/xpl/login.jsp?tp=&arnumber=6433729&url=http%3A%2F%2Fieeexplore.ieee.org%2Fstamp%2Fstamp.jsp%3Ftp%3D%26arnumber%3D6433729
^ " by Marcus Bowman Crowood, 31 August 2015, Crafts & Hobbies
^ "Low price measuring magnifier uses real glass reticle", Journal of the Franklin Institute, 1955, Vol. 259(6), pp. 516–516 [peer reviewed journal]
^ Charles C. Ryerson and Anthony J. Gow: Ship Superstructure Icing: Crystalline and Physical Properties in: US Army Corps of Engineers® Engineer Research and Development Center (August 2000) p. 14
^ van Altena, W. F., Low-luminosity members of the Hyades cluster. Astronomical Journal, Vol. 71, p. 482–512 (1966)
^ I. B. A. Menown, G. MacKenzie and A. A. J. Adgey, Optimizing the initial 12-lead electrocardiographic diagnosis of acute myocardial infarction, European Heart Journal (2000) 21, 275–283
^ DEPARTMENT OF THE ARMY EM 1110-2-2002 U.S. Army Corps of Engineers: EVALUATION AND REPAIR OF CONCRETE STRUCTURES p.2-11 http://www.publications.usace.army.mil/Portals/76/Publications/EngineerManuals/EM_1110-2-2002.pdf
^ The Pocket Comparator: A New Measuring Instrument, in: INDUSTRIAL QUALITY CONTROL VOL.6 NO.5, March 1950 pp. 22-23

[1] "The Pocket Comparator - A New Optical Measuring Instrument". in: Electrical Engineering (Volume 69, Issue 3, p. 220) March 1950 http://ieeexplore.ieee.org/xpl/login.jsp?tp=&arnumber=6433729&url=http%3A%2F%2Fieeexplore.ieee.org%2Fstamp%2Fstamp.jsp%3Ftp%3D%26arnumber%3D6433729

[2] " by Marcus Bowman Crowood, 31 August 2015, Crafts & Hobbies

[3] "Low price measuring magnifier uses real glass reticle", Journal of the Franklin Institute, 1955, Vol. 259(6), pp. 516–516 [peer reviewed journal]

[4] Charles C. Ryerson and Anthony J. Gow: Ship Superstructure Icing: Crystalline and Physical Properties in: US Army Corps of Engineers® Engineer Research and Development Center (August 2000) p. 14

[5] van Altena, W. F., Low-luminosity members of the Hyades cluster. Astronomical Journal, Vol. 71, p. 482–512 (1966)

[6] I. B. A. Menown, G. MacKenzie and A. A. J. Adgey, Optimizing the initial 12-lead electrocardiographic diagnosis of acute myocardial infarction, European Heart Journal (2000) 21, 275–283

[7] DEPARTMENT OF THE ARMY EM 1110-2-2002 U.S. Army Corps of Engineers: EVALUATION AND REPAIR OF CONCRETE STRUCTURES p.2-11 http://www.publications.usace.army.mil/Portals/76/Publications/EngineerManuals/EM_1110-2-2002.pdf

[8] The Pocket Comparator: A New Measuring Instrument, in: INDUSTRIAL QUALITY CONTROL VOL.6 NO.5, March 1950 pp. 22-23

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