Table detailing the alphabet used to communicate using a double-needle telegraph system. One of the two main types of electromagnetic telegraphs, needle telegraphs use indicating needles moved electromagnetically as a means of displaying messages.
Ward, Lock. “Double-Needle Alphabet.” Wonders of Electricity and the Elements, Being a Popular Account of Modern Electrical and Magnetic Discoveries, Magnetism and Electric Machines, the Electric Telegraph and the Electric Light, and the Metal Bases, Salt, and Acids. London, England, 1870–1900. https://digital.sciencehistory.org/works/bwjgz5z.
Mouse click to zoom in; shift-click to zoom out. Drag to pan. Pinch to zoom on touch.
The Science History Institute recognizes there are materials in our collections that may be offensive or harmful, containing racist, sexist, Eurocentric, ableist, or homophobic language or depictions. The history of science is not exempt from beliefs or practices harmful to traditionally marginalized groups. The Institute is engaged in ongoing efforts to responsibly present and address the evidence of oppression and injustice inextricable from the history of science. If you would like to learn more about our ongoing efforts or if you encounter harmful, inaccurate, or insufficient descriptions, please contact us at firstname.lastname@example.org.