The work of the Observatory was essentially related to the distribution of time signals. The director, Jules Baillaud (1876-1960), worked with General Gustave Ferrié (1868-1932) to transmit time signals from the Eiffel Tower, which helped save it from being dismantled.

caption : Time transmission with the Eiffel Tower - credits : Observatoire de Paris

To know more : Wireless transmission of time signals