Date: February, 24,1961

At my Augmentation Research Center at SRI with Bill English, we decided to research a way to make it easier to interact with machines. We decide to research some screen select devices, with the goal of finding the easiest way to point and select on the screen. We created a chart that listed all the advantages and disadvantages of each device. For example, one of the advantages and disadvantages of the light pen was that it was simple to use, but the problem was you had to pick it up and put it down and that became tiresome.

This was similar to how the periodic table’s rules led to the discovery of unknown elements since it helped us define the ultimate desirable characteristics for a device that didn’t exist. One day when I was in a conference I started to daydream about a device from high school called a Planimeter that calculated the area of a space by being rolled around its perimeter. The way the Planimeter works is it  has two wheels, one horizontal and one vertical, to add up the distance it was rolled in each direction. Thinking about that made me start to sketch out how a screen select device could work in the same way. The device could roll around a desktop on two wheels, and depending on the direction of the roll, it would either register high voltages or low voltages.

I gave the sketch to Bill English who carved out a piece of mahogany to make the first model. I wanted to put up to ten buttons on the mouse but the optimum number of buttons for the mouse turned out to be three. There were two reasons we decided to call it a mouse, one was because we tried having the cord come out of the front but then we moved it to the back since that worked better and so that made it look like mouse. Reason two was because Bill said the term for cursor used to be CAT but he couldn't remember why, but it seemed the cursor was chasing the mouse. The mouse was our optimal choice for computer interaction since it made excellent work of hand eye coordination.