Francis Blake, Jr. (1850 – 1913) was born in Needham, Massachusetts, the son of Caroline Burling (Trumbull) and Francis Blake, Sr. and died in Weston, Massachusetts.
In 1877 Francis Blake invented a carbon microphone for use in the telephone, shortly after Thomas Edison invented a microphone that also used carbon contacts. Blake used a carbon button design that initially would not stay in adjustment, but with later improvements proved to be workable. Alexander Graham Bell hired Blake and put him to work with Emile Berliner who also invented a carbon microphone. The improved Berliner-Blake microphone was standard with the Bell company for many years.
Blake worked on the United States Coast Survey from his teenage years through early adulthood (1866-1878). He was a physicist and an amateur photographer.
In 1874 Blake married Elizabeth Livermore Hubbard (1849-1941) whose father provided land in Weston on which Blake designed and built an elaborate house in which Blake conducted his electrical experiments. They had two children: Agnes (Blake) Fitzgerald (b. 1876) and Benjamin Sewall Blake (b. 1877).
Blake was elected a member of the American Antiquarian Society in 1900.Canadian patent 10021 for telephone transmitter, granted 28 May 1879, voided 3 March, 1887 because of failure to manufacture telephone parts in Canada.
US patent granted in 1881