In which year did Douglas Car Engelbart receive a patent for a computer mouse?

Douglas Carl Engelbart (January 30, 1925 – July 2, 2013) was an American engineer and inventor, and an early computer and Internet pioneer. He is best known for his work on founding the field of human-computer interaction, particularly while at his Augmentation Research Center Lab in SRI International, which resulted in the creation of the computer mouse, and the development of hypertext, networked computers, and precursors to graphical user interfaces. These were demonstrated at The Mother of All Demos in 1968. Engelbart's law, the observation that the intrinsic rate of human performance is exponential, is named after him.

Engelbart applied for a patent in 1967 and received it in 1970, for the wooden shell with two metal wheels (computer mouse – U.S. Patent 3,541,541), which he had developed with Bill English, his lead engineer, sometime before 1965. In the patent application, it is described as an "X-Y position indicator for a display system". Engelbart later revealed that it was nicknamed the "mouse" because the tail came out the end. His group also called the on-screen cursor a "bug", but this term was not widely adopted.