My answer was going to be by the sun. If I were blind, I could still feel the sun on my skin, and through that feeling, know the time.<br />
Other than the sun, I would measure time by the growth and interests of my children, and my children's children.
A psychological progression. Although, not necessarily linear. Time is probably a mind thing mostly
It's already been written. Time would be measured by the journey of the sun. I chose the word "journey" for good reason. The root word is "jour" which is day in French.<br />
As a 14 year old desperate for pocket money I'd work all Summer on a cash-crop farm. Day after day of non-stop howing and pruning. By the start of August I discovered I could tell the time with 3-4 minutes accuracy by observing the sun and dead-reckoning its position in relation to fixed ob<x>jects in the foreground. <br />
That's what I know of time via personal observation. In truth, I know it was created by God when he envisioned "night and day". God existed for all eternity and the only way the human mind can come close to comprehending that- is to remember that God created time and he is not subject to it.<br />
If we were not aware of time--we'd lose perspective and many other things. <br />
As I grow older I'm aware my time for getting things done, grows short and I recall how quickly and easily a decade passes. In 7 months it'll be the 10th anniversary of 9/11. That was alarmingly fast.<br />
By stable processes, eg. oscillations of the cesium atom. You could also use the speed of light, to measure time by the distance it travels (speed of light is constant).<br />
But, I think you are alluding to the question, what if it was impossible to measure time? Then applying the usual principles of physics in such a circumstance the concept of time should not enter in the desc<x>ription. Hence time would not exist.<br />
What is apparent though in the case when you can measure time is that it is a counting of events, where events are usually a collection of particle interactions. Thus in a universe where no particles could interact time doesn't exist, because an unmeasurable quantity is useless.