On June 21, 1880, Bell's assistant transmitted a wireless voice telephone message a considerable distance, from the roof of the Franklin School in Washington, D.C., to Bell at the window of his laboratory, some 213 metres (700 ft) away, 19 years before the first voice radio transmissions.
How many feet did the first photophone message travel?
700
On June 21, 1880, Bell's assistant transmitted a wireless voice telephone message a considerable distance, from the roof of the Franklin School in Washington, D.C., to Bell at the window of his laboratory, some 213 metres (700 ft) away, 19 years before the first voice radio transmissions.
On June twenty-one, eighteen eighty, Bell's assistant transmitted a wireless voice telephone message a considerable distance, from the roof of the Franklin School in Washington, D.C., to Bell at the window of his laboratory, some two hundred thirteen metres (seven hundred ft) away, nineteen years before the first voice radio transmissions.
How many feet did the first photophone message travel?