Optical instruments
Half-title page: Summary technical report of the National Defense Research Committee. "Manuscript and illustrations for this volume were prepared for publication by the Summary Reports Group of the Columbia Uni... More
Frank S. Betz Co., (Optical Instruments, etc.,) Hammond, Ind. Very few...
Picryl description: Public domain image of girl workers, child labor, working children, economic conditions, free to use, no copyright restrictions.
Drawings by Alexander Graham Bell?, from June 25, 1881 to December 26,...
Public domain photograph of a machine part, motor, equipment, free to use, no copyright restrictions image - Picryl description
Journal by Alexander Graham Bell, from July 19, 1901 to August 31, 190...
Alexander Graham Bell Papers. Public domain photograph of laboratory, science, research, free to use, no copyright restrictions image - Picryl description
Drawings by Alexander Graham Bell?, from June 25, 1881 to December 26,...
Public domain photograph related to development of telegraph, free to use, no copyright restrictions image - Picryl description
Drawings by Alexander Graham Bell?, from June 25, 1881 to December 26,...
Public domain photograph related to development of telegraph, free to use, no copyright restrictions image - Picryl description
Optical instruments
Half-title page: Summary technical report of the National Defense Research Committee. "Manuscript and illustrations for this volume were prepared for publication by the Summary Reports Group of the Columbia Uni... More
Journal by Alexander Graham Bell, from July 19, 1901 to August 31, 190...
Alexander Graham Bell Papers. Public domain photograph of laboratory, science, research, free to use, no copyright restrictions image - Picryl description
Optical instruments
Half-title page: Summary technical report of the National Defense Research Committee. "Manuscript and illustrations for this volume were prepared for publication by the Summary Reports Group of the Columbia Uni... More
Journal by Alexander Graham Bell, from July 19, 1901 to August 31, 190...
Alexander Graham Bell Papers. Public domain photograph of laboratory, science, research, free to use, no copyright restrictions image - Picryl description
Optical instruments
Half-title page: Summary technical report of the National Defense Research Committee. "Manuscript and illustrations for this volume were prepared for publication by the Summary Reports Group of the Columbia Uni... More
Journal by Alexander Graham Bell, from July 19, 1901 to August 31, 190...
Alexander Graham Bell Papers. Public domain photograph of laboratory, science, research, free to use, no copyright restrictions image - Picryl description
Journal by Alexander Graham Bell, from July 19, 1901 to August 31, 190...
Alexander Graham Bell Papers. Public domain photograph of laboratory, science, research, free to use, no copyright restrictions image - Picryl description
Journal by Alexander Graham Bell, from July 19, 1901 to August 31, 190...
Alexander Graham Bell Papers. Public domain photograph of laboratory, science, research, free to use, no copyright restrictions image - Picryl description
Journal by Alexander Graham Bell, from July 19, 1901 to August 31, 190...
Alexander Graham Bell Papers. Public domain photograph of laboratory, science, research, free to use, no copyright restrictions image - Picryl description
Journal by Alexander Graham Bell, from July 19, 1901 to August 31, 190...
Alexander Graham Bell Papers. Public domain photograph of laboratory, science, research, free to use, no copyright restrictions image - Picryl description
Optical instruments
Half-title page: Summary technical report of the National Defense Research Committee. "Manuscript and illustrations for this volume were prepared for publication by the Summary Reports Group of the Columbia Uni... More
Optical instruments
Half-title page: Summary technical report of the National Defense Research Committee. "Manuscript and illustrations for this volume were prepared for publication by the Summary Reports Group of the Columbia Uni... More
Optical instruments
Half-title page: Summary technical report of the National Defense Research Committee. "Manuscript and illustrations for this volume were prepared for publication by the Summary Reports Group of the Columbia Uni... More
Journal by Alexander Graham Bell, from July 19, 1901 to August 31, 190...
Alexander Graham Bell Papers. Public domain photograph of laboratory, science, research, free to use, no copyright restrictions image - Picryl description
Journal by Alexander Graham Bell, from July 19, 1901 to August 31, 190...
Alexander Graham Bell Papers. Public domain photograph of laboratory, science, research, free to use, no copyright restrictions image - Picryl description
Optical instruments
Half-title page: Summary technical report of the National Defense Research Committee. "Manuscript and illustrations for this volume were prepared for publication by the Summary Reports Group of the Columbia Uni... More
Optical instruments
Half-title page: Summary technical report of the National Defense Research Committee. "Manuscript and illustrations for this volume were prepared for publication by the Summary Reports Group of the Columbia Uni... More
Journal by Alexander Graham Bell, from July 19, 1901 to August 31, 190...
Alexander Graham Bell Papers. Public domain photograph of laboratory, science, research, free to use, no copyright restrictions image - Picryl description
Optical instruments
Half-title page: Summary technical report of the National Defense Research Committee. "Manuscript and illustrations for this volume were prepared for publication by the Summary Reports Group of the Columbia Uni... More
Journal by Alexander Graham Bell, from July 19, 1901 to August 31, 190...
Alexander Graham Bell Papers. Public domain photograph of laboratory, science, research, free to use, no copyright restrictions image - Picryl description
Optical instruments
Half-title page: Summary technical report of the National Defense Research Committee. "Manuscript and illustrations for this volume were prepared for publication by the Summary Reports Group of the Columbia Uni... More
Optical instruments
Half-title page: Summary technical report of the National Defense Research Committee. "Manuscript and illustrations for this volume were prepared for publication by the Summary Reports Group of the Columbia Uni... More
Optical instruments
Half-title page: Summary technical report of the National Defense Research Committee. "Manuscript and illustrations for this volume were prepared for publication by the Summary Reports Group of the Columbia Uni... More
Journal by Alexander Graham Bell, from July 19, 1901 to August 31, 190...
Alexander Graham Bell Papers. Public domain photograph of laboratory, science, research, free to use, no copyright restrictions image - Picryl description
Optical instruments
Half-title page: Summary technical report of the National Defense Research Committee. "Manuscript and illustrations for this volume were prepared for publication by the Summary Reports Group of the Columbia Uni... More
Optical instruments
Half-title page: Summary technical report of the National Defense Research Committee. "Manuscript and illustrations for this volume were prepared for publication by the Summary Reports Group of the Columbia Uni... More
Optical instruments
Half-title page: Summary technical report of the National Defense Research Committee. "Manuscript and illustrations for this volume were prepared for publication by the Summary Reports Group of the Columbia Uni... More
Optical instruments
Half-title page: Summary technical report of the National Defense Research Committee. "Manuscript and illustrations for this volume were prepared for publication by the Summary Reports Group of the Columbia Uni... More
Optical instruments
Half-title page: Summary technical report of the National Defense Research Committee. "Manuscript and illustrations for this volume were prepared for publication by the Summary Reports Group of the Columbia Uni... More
Optical instruments
Half-title page: Summary technical report of the National Defense Research Committee. "Manuscript and illustrations for this volume were prepared for publication by the Summary Reports Group of the Columbia Uni... More
Optical instruments
Half-title page: Summary technical report of the National Defense Research Committee. "Manuscript and illustrations for this volume were prepared for publication by the Summary Reports Group of the Columbia Uni... More
Optical instruments
Half-title page: Summary technical report of the National Defense Research Committee. "Manuscript and illustrations for this volume were prepared for publication by the Summary Reports Group of the Columbia Uni... More
Optical instruments
Half-title page: Summary technical report of the National Defense Research Committee. "Manuscript and illustrations for this volume were prepared for publication by the Summary Reports Group of the Columbia Uni... More
Optical instruments
Half-title page: Summary technical report of the National Defense Research Committee. "Manuscript and illustrations for this volume were prepared for publication by the Summary Reports Group of the Columbia Uni... More
Optical instruments
Half-title page: Summary technical report of the National Defense Research Committee. "Manuscript and illustrations for this volume were prepared for publication by the Summary Reports Group of the Columbia Uni... More
Optical instruments
Half-title page: Summary technical report of the National Defense Research Committee. "Manuscript and illustrations for this volume were prepared for publication by the Summary Reports Group of the Columbia Uni... More
Optical instruments
Half-title page: Summary technical report of the National Defense Research Committee. "Manuscript and illustrations for this volume were prepared for publication by the Summary Reports Group of the Columbia Uni... More
Optical instruments
Half-title page: Summary technical report of the National Defense Research Committee. "Manuscript and illustrations for this volume were prepared for publication by the Summary Reports Group of the Columbia Uni... More
Optical instruments
Half-title page: Summary technical report of the National Defense Research Committee. "Manuscript and illustrations for this volume were prepared for publication by the Summary Reports Group of the Columbia Uni... More
Optical instruments
Half-title page: Summary technical report of the National Defense Research Committee. "Manuscript and illustrations for this volume were prepared for publication by the Summary Reports Group of the Columbia Uni... More
Optical instruments
Half-title page: Summary technical report of the National Defense Research Committee. "Manuscript and illustrations for this volume were prepared for publication by the Summary Reports Group of the Columbia Uni... More
Optical instruments
Half-title page: Summary technical report of the National Defense Research Committee. "Manuscript and illustrations for this volume were prepared for publication by the Summary Reports Group of the Columbia Uni... More
Optical instruments
Half-title page: Summary technical report of the National Defense Research Committee. "Manuscript and illustrations for this volume were prepared for publication by the Summary Reports Group of the Columbia Uni... More
Optical instruments
Half-title page: Summary technical report of the National Defense Research Committee. "Manuscript and illustrations for this volume were prepared for publication by the Summary Reports Group of the Columbia Uni... More
Optical instruments
Half-title page: Summary technical report of the National Defense Research Committee. "Manuscript and illustrations for this volume were prepared for publication by the Summary Reports Group of the Columbia Uni... More
Optical instruments
Half-title page: Summary technical report of the National Defense Research Committee. "Manuscript and illustrations for this volume were prepared for publication by the Summary Reports Group of the Columbia Uni... More
Optical instruments
Half-title page: Summary technical report of the National Defense Research Committee. "Manuscript and illustrations for this volume were prepared for publication by the Summary Reports Group of the Columbia Uni... More
Optical instruments
Half-title page: Summary technical report of the National Defense Research Committee. "Manuscript and illustrations for this volume were prepared for publication by the Summary Reports Group of the Columbia Uni... More
Optical instruments
Half-title page: Summary technical report of the National Defense Research Committee. "Manuscript and illustrations for this volume were prepared for publication by the Summary Reports Group of the Columbia Uni... More
Optical instruments
Half-title page: Summary technical report of the National Defense Research Committee. "Manuscript and illustrations for this volume were prepared for publication by the Summary Reports Group of the Columbia Uni... More
Optical instruments
Half-title page: Summary technical report of the National Defense Research Committee. "Manuscript and illustrations for this volume were prepared for publication by the Summary Reports Group of the Columbia Uni... More
Optical instruments
Half-title page: Summary technical report of the National Defense Research Committee. "Manuscript and illustrations for this volume were prepared for publication by the Summary Reports Group of the Columbia Uni... More
Optical instruments
Half-title page: Summary technical report of the National Defense Research Committee. "Manuscript and illustrations for this volume were prepared for publication by the Summary Reports Group of the Columbia Uni... More
Optical instruments
Half-title page: Summary technical report of the National Defense Research Committee. "Manuscript and illustrations for this volume were prepared for publication by the Summary Reports Group of the Columbia Uni... More
Optical instruments
Half-title page: Summary technical report of the National Defense Research Committee. "Manuscript and illustrations for this volume were prepared for publication by the Summary Reports Group of the Columbia Uni... More
Optical instruments
Half-title page: Summary technical report of the National Defense Research Committee. "Manuscript and illustrations for this volume were prepared for publication by the Summary Reports Group of the Columbia Uni... More
Optical instruments
Half-title page: Summary technical report of the National Defense Research Committee. "Manuscript and illustrations for this volume were prepared for publication by the Summary Reports Group of the Columbia Uni... More
Optical instruments
Half-title page: Summary technical report of the National Defense Research Committee. "Manuscript and illustrations for this volume were prepared for publication by the Summary Reports Group of the Columbia Uni... More
Optical instruments
Half-title page: Summary technical report of the National Defense Research Committee. "Manuscript and illustrations for this volume were prepared for publication by the Summary Reports Group of the Columbia Uni... More
Optical instruments
Half-title page: Summary technical report of the National Defense Research Committee. "Manuscript and illustrations for this volume were prepared for publication by the Summary Reports Group of the Columbia Uni... More
Optical instruments
Half-title page: Summary technical report of the National Defense Research Committee. "Manuscript and illustrations for this volume were prepared for publication by the Summary Reports Group of the Columbia Uni... More
Optical instruments
Half-title page: Summary technical report of the National Defense Research Committee. "Manuscript and illustrations for this volume were prepared for publication by the Summary Reports Group of the Columbia Uni... More
Optical instruments
Half-title page: Summary technical report of the National Defense Research Committee. "Manuscript and illustrations for this volume were prepared for publication by the Summary Reports Group of the Columbia Uni... More
Optical instruments
Half-title page: Summary technical report of the National Defense Research Committee. "Manuscript and illustrations for this volume were prepared for publication by the Summary Reports Group of the Columbia Uni... More
Optical instruments
Half-title page: Summary technical report of the National Defense Research Committee. "Manuscript and illustrations for this volume were prepared for publication by the Summary Reports Group of the Columbia Uni... More
Optical instruments
Half-title page: Summary technical report of the National Defense Research Committee. "Manuscript and illustrations for this volume were prepared for publication by the Summary Reports Group of the Columbia Uni... More
Journal by Alexander Graham Bell, from July 19, 1901 to August 31, 190...
Alexander Graham Bell Papers. Public domain photograph of laboratory, science, research, free to use, no copyright restrictions image - Picryl description
Optical instruments
Half-title page: Summary technical report of the National Defense Research Committee. "Manuscript and illustrations for this volume were prepared for publication by the Summary Reports Group of the Columbia Uni... More
Journal by Alexander Graham Bell, from July 19, 1901 to August 31, 190...
Alexander Graham Bell Papers. Public domain photograph of laboratory, science, research, free to use, no copyright restrictions image - Picryl description
Journal by Alexander Graham Bell, from July 19, 1901 to August 31, 190...
Alexander Graham Bell Papers. Public domain photograph of laboratory, science, research, free to use, no copyright restrictions image - Picryl description
Optical instruments
Half-title page: Summary technical report of the National Defense Research Committee. "Manuscript and illustrations for this volume were prepared for publication by the Summary Reports Group of the Columbia Uni... More
Journal by Alexander Graham Bell, from July 19, 1901 to August 31, 190...
Alexander Graham Bell Papers. Public domain photograph of laboratory, science, research, free to use, no copyright restrictions image - Picryl description
Journal by Alexander Graham Bell, from July 19, 1901 to August 31, 190...
Alexander Graham Bell Papers. Public domain photograph of laboratory, science, research, free to use, no copyright restrictions image - Picryl description
Journal by Alexander Graham Bell, from July 19, 1901 to August 31, 190...
Alexander Graham Bell Papers. Public domain photograph of laboratory, science, research, free to use, no copyright restrictions image - Picryl description
Optical instruments
Half-title page: Summary technical report of the National Defense Research Committee. "Manuscript and illustrations for this volume were prepared for publication by the Summary Reports Group of the Columbia Uni... More
Journal by Alexander Graham Bell, from July 19, 1901 to August 31, 190...
Alexander Graham Bell Papers. Public domain photograph of laboratory, science, research, free to use, no copyright restrictions image - Picryl description
Optical instruments
Half-title page: Summary technical report of the National Defense Research Committee. "Manuscript and illustrations for this volume were prepared for publication by the Summary Reports Group of the Columbia Uni... More
Optical instruments
Half-title page: Summary technical report of the National Defense Research Committee. "Manuscript and illustrations for this volume were prepared for publication by the Summary Reports Group of the Columbia Uni... More
Optical instruments
Half-title page: Summary technical report of the National Defense Research Committee. "Manuscript and illustrations for this volume were prepared for publication by the Summary Reports Group of the Columbia Uni... More
Optical instruments
Half-title page: Summary technical report of the National Defense Research Committee. "Manuscript and illustrations for this volume were prepared for publication by the Summary Reports Group of the Columbia Uni... More
Optical instruments
Half-title page: Summary technical report of the National Defense Research Committee. "Manuscript and illustrations for this volume were prepared for publication by the Summary Reports Group of the Columbia Uni... More
Journal by Alexander Graham Bell, from July 19, 1901 to August 31, 190...
Alexander Graham Bell Papers. Public domain photograph of laboratory, science, research, free to use, no copyright restrictions image - Picryl description
Optical instruments
Half-title page: Summary technical report of the National Defense Research Committee. "Manuscript and illustrations for this volume were prepared for publication by the Summary Reports Group of the Columbia Uni... More
Journal by Alexander Graham Bell, from July 19, 1901 to August 31, 190...
Alexander Graham Bell Papers. Public domain photograph of laboratory, science, research, free to use, no copyright restrictions image - Picryl description
Optical instruments
Half-title page: Summary technical report of the National Defense Research Committee. "Manuscript and illustrations for this volume were prepared for publication by the Summary Reports Group of the Columbia Uni... More
Journal by Alexander Graham Bell, from July 19, 1901 to August 31, 190...
Alexander Graham Bell Papers. Public domain photograph of laboratory, science, research, free to use, no copyright restrictions image - Picryl description
Journal by Alexander Graham Bell, from July 19, 1901 to August 31, 190...
Alexander Graham Bell Papers. Public domain photograph of laboratory, science, research, free to use, no copyright restrictions image - Picryl description
Journal by Alexander Graham Bell, from July 19, 1901 to August 31, 190...
Alexander Graham Bell Papers. Public domain photograph of laboratory, science, research, free to use, no copyright restrictions image - Picryl description
Optical instruments
Half-title page: Summary technical report of the National Defense Research Committee. "Manuscript and illustrations for this volume were prepared for publication by the Summary Reports Group of the Columbia Uni... More
Optical instruments
Half-title page: Summary technical report of the National Defense Research Committee. "Manuscript and illustrations for this volume were prepared for publication by the Summary Reports Group of the Columbia Uni... More
Journal by Alexander Graham Bell, from July 19, 1901 to August 31, 190...
Alexander Graham Bell Papers. Public domain photograph of laboratory, science, research, free to use, no copyright restrictions image - Picryl description
Journal by Alexander Graham Bell, from July 19, 1901 to August 31, 190...
Alexander Graham Bell Papers. Public domain photograph of laboratory, science, research, free to use, no copyright restrictions image - Picryl description