Bell's Photophone

Alexander Graham Bell (detail),
Timoléon Lobrichon, artist,
photoprint of 1882 painting.
Prints and Photographs Division

On June 3, 1880, Alexander Graham Bell transmitted the first wireless telephone message on his newly invented photophone from the top of the Franklin School in Washington, D.C.

Franklin School, Wash., D.C.
Frances Benjamin Johnston, photographer,
Photographic print, [ca. 1900].
Prints & Photographs Online Catalog

Bell believed that the photophone was his most important invention. The device allowed the transmission of sound on a beam of light. Of the eighteen patents granted in Bell's name alone, and the twelve that he shared with his collaborators, four were for the photophone.

Bell's photophone worked by projecting the voice through an instrument toward a mirror. Vibrations in the voice caused similar vibrations in the mirror. Bell directed sunlight into the mirror, which captured and projected the mirror's vibrations. The vibrations were transformed back into sound at the receiving end of the projection. The photophone functioned similarly to the telephone, except that the photophone used light as a means of projecting the information and the telephone relied on electricity.

Although the photophone was an extremely important invention, it was many years before the significance of Bell's work was fully recognized. Bell's original photophone failed to protect transmissions from outside interferences—such as clouds, that easily disrupted transport. Until the development of modern fiber optics, technology for the secure transport of light inhibited use of Bell's invention. Bell's photophone is recognized as the progenitor of modern fiber optics.

The Library of Congress has a multitude of information related to Bell's life. Search the following collections:

• The Alexander Graham Bell Family Papers contain correspondence, scientific notebooks, journals, blueprints, speeches, and photographs documenting Bell's invention of the telephone and his involvement in the first telephone company, his family life, his interest in the education of the deaf, and his aeronautical and other scientific research. Use the Timeline to learn more about the inventor or peruse some of the Collection Highlights. To dig deeper into the collection, browse the different series of papers or search on terms of special interest.
• The American Memory collection The Nineteenth Century in Print: Periodicals contains numerous articles about Alexander Graham Bell. News of his most recent inventions was certain to be documented in the scientific and technical literature of the time such as Manufacturer and Builder.
• The Library's Prints & Photographs Online Catalog contains over one million images and Alexander Graham Bell's family life and work is extensively documented.
• Learn more about the inventor. A biography of Bell is featured on the March 10 Today in History. Also, see the feature on the National Geographic Society of which Bell was a founder and first president.
• Search the Today in History Archive on the keywords inventor or invention to find more portraits of creative Americans including Samuel F. B. Morse, Elias Howe, and Henry Ford.

Battle of Cold Harbor

Cold Harbor, Va. Gen. Burnside and his staff at 9th Corps headquarters,
Engraving from a photograph by Mathew Brady,
July 23, 1864.
Civil War Photographs, 1861-1865

On June 3, 1864, the second battle of Cold Harbor began. After securing a costly victory at the Battle of Spotsylvania Court House, Union General Ulysses S. Grant encountered Confederate troops as he made his way to Richmond. The Confederates, under command of General Robert E. Lee, were entrenched behind earthworks at Cold Harbor, a crossroads ten miles northeast of the Confederate capital. Over the course of the next nine days, the Union lost 7,000 men while the Confederates suffered 1,500 casualties. Grant moved on toward Petersburg and began the last major siege of the war. Confederate forces finally abandoned Petersburg and Richmond on April 2, 1865.

The first battle of Cold Harbor, also called the battle of Gaines' Mill, took place on June 27, 1862. It was part of the Seven Days' Battles (June 25-July 1) that ended General George McClellan's Peninsular Campaign -- an early attempt to capture the Confederate capital.

Learn more about the Civil War in American Memory:

• View photographs from the war. Civil War Photographs, 1861-1865 includes eight photographs of Cold Harbor, Virginia.
• Search Military Battles and Campaigns in Map Collections on keywords such as Petersburg, Richmond, and Cold Harbor for dozens of maps of these battles.
• Read eyewitness accounts of the Civil War. First-Person Narratives of the American South, 1860-1920 documents the culture of the nineteenth-century American South from the viewpoint of Southerners. Search the collection on Civil War to read books such as A Boy's Experience in the Civil War, 1860-1865.
• For additional information about the Civil War, search the Today in History Archive on Civil War to locate features highlighting:
  • General Lee's evacuation of Richmond;
  • Military engagements at Bull Run, Gettysburg, Nashville, and Antietam; and
  • Other key figures from the Civil War era such as Jefferson Davis and Stonewall Jackson as well as Civil War era events including Abraham Lincoln's Gettysburg Address and the execution of Andersonville Prison's Henry Wirz.
• Consult Primary Documents in American History: Civil War and Reconstruction, 1860-1877 for links to digitized materials on this era.