Library Of Congress
Library Of CongressPublic Domain ArchivePart of PICRYL.com. Not developed or endorsed by the Library of Congress
Government discovers method to preserve film. (2) Expansion and contraction, like paper and other sheet materials made from cellulose, films expand as they take up moisture and contract as they lose it, and the extent of the change is different in the two directions of them. This may cause some distortion of the image, and therefore is of particular importance where the image must be true to scale, such as in aerial photography. C.O. Pope is shown with a type of expansiveity tester used and which was designed by the Bureau of Standards. Long strips of film are suspended under constant tension in the [cabinet?] in which the humidity is varied by means of [...] solutions. The change in length is indicated [...continuously?] on a scale by means of an optical-level arrangement, 7/8/38

Government discovers method to preserve film. (2) Expansion and contraction, like paper and other sheet materials made from cellulose, films expand as they take up moisture and contract as they lose it, and the extent of the change is different in the two directions of them. This may cause some distortion of the image, and therefore is of particular importance where the image must be true to scale, such as in aerial photography. C.O. Pope is shown with a type of expansiveity tester used and which was designed by the Bureau of Standards. Long strips of film are suspended under constant tension in the [cabinet?] in which the humidity is varied by means of [...] solutions. The change in length is indicated [...continuously?] on a scale by means of an optical-level arrangement, 7/8/38

 
 

Explorecontraction

Library Of Congress

The objects in this archive are from Library of Congress - the nation’s first established cultural institution and the largest library in the world, with millions of items including books, recordings, photographs, maps and manuscripts in its collections. The Library provides Congress, the federal government and the American people with a rich, diverse and enduring source of knowledge to inform, inspire and engage them and support their intellectual and creative endeavors.

Disclaimer: A work of the Library of Congress is "a work prepared by an officer or employee" of the federal government "as part of that person's official duties." In general, under section 105 of the Copyright Act, such works are not entitled to domestic copyright protection under U.S. law and are therefore in the public domain. This website is developed as a part of the world's largest public domain archive, PICRYL.com, and not developed or endorsed by the Library of Congress,  https://www.picryl.com

Developed by GetArchive, 2015-2021