Touch-tone telephone

The invention: 

A push-button dialing system for telephones that
replaced the earlier rotary-dial phone.

The person behind the invention:

Bell Labs, the research and development arm of the American
Telephone and Telegraph Company

Tidal power plant

The invention:

Plant that converts the natural ocean tidal forces
into electrical power.

The people behind the invention:

Mariano di Jacopo detto Taccola (Mariano of Siena, 1381-1453),
an Italian notary, artist, and engineer
Bernard Forest de Bélidor (1697 or 1698-1761), a French engineer
Franklin D. Roosevelt (1882-1945), president of the United States