A former naval radar technician, Doug Engelbart, directed the invention of the first computer mouse in the mid 60s at Stanford Research International (SRI). Engelbart and Bill English worked together comparing various pointing devices for speed and accuracy. Bill English built the original mouse from Engelbart's conceptions. So, "It is safe to say Bill English is the first person to ever use a mouse." [Computer History Museum]
The first mouse only vaguely resembles the computer mouse stereotype we know today. It is encased in a large hand carved wooden block with room for only one button. Engelbart's and English's 1963 mouse had two wheels perpendicular to the desktop and to each other to mark the X-Y position in response to its movement by hand over a surface. A peg on the opposite corner offset the wheels. [Doug Engelbart Institute]
Engelbart's research to augment human intellect led to his development of NLS (oN-Line System) for manipulating documents, which he demonstrated publically in 1968 [Doug Engelbart Institute]. The left hand operated his chording keyset while the right hand operated the mouse.
The later model mouse used for Engelbart's NLS presentation is also a tall mouse by contemporary mouse standards, to accommodate the wheels. It has three buttons, as illustrated in the 1967 patent application for the "X-Y Position Indicator for a Display System." U.S. Patent 3,541,541 was issued to Stanford Research Institute in 1970. The patent illustration shows a three button mouse with the cord coming out of the wrist end of a plastic case, along with a keyboard inside a typewriter-looking housing, and a round screen display in a box. [Patent3541541.pdf 565K]
The mouse in the patent application has a ball bearing to provide support. Potentiometers (rheostats) attached to the disk communicate signals through a wire to the computer and on to the video display. The buttons close switches attached to other wires. Direct digital pulses are generated by a shaft position encoder, as opposed to an analog signal converted to digital, so this is the first digital mouse. Its nickname "mouse" persisted over its formal name.
The inventor suggests this invention offers improvement over a light pencil because the operator does not need to have one hand against the CRT, can keep both hands close by for entering keyboard changes, and the device does not block part of the screen when in place.