Image: Signaling by Napoleonic semaphore line

Description: Illustration of communication by mechanical semaphore in 1800s France. Lines of towers supporting semaphore masts were built within visual distance of each other. The arms of the semaphore were moved to different positions, to spell out text messages. The operators in the next tower would read the message and pass it on. Invented by Claude Chappee in 1792, semaphore was a popular communication technology in the early 19th century until the telegraph replaced it.
Title: Signaling by Napoleonic semaphore line
Credit: Retrieved June 11, 2014 from Radio News magazine, Ziff-Davis Publishing Co., Inc., New York, Vol. 32, No. 5, November 1944, p. 71 archived on http://www.americanradiohistory.com/
Author: The drawing is signed "Keith Thomas" in lower right corner
Permission: This image is from an advertisement by Universal Microphone Co. without a copyright notice published in a 1944 magazine. In the United States, advertisements published in collective works (magazines and newspapers) are not covered by the copyright notice for the entire collective work. (See U.S. Copyright Office Circular 3, "Copyright Notice", page 3, "Contributions to Collective Works".) Since the advertisement was published before 1978 without a copyright notice, it falls into the public domain.
Usage Terms: Public domain
License: Public domain
Attribution Required?: No