Occasionally I see two clocks together with slightly different times displayed and it occurs to me that those two machines are just sitting there counting. One is counting a little faster than the other and each displays how far it has counted and we consider that a measurement of time.
Consider what's inside a clock. The old fashioned grandfather clock with a pendulum swinging back and forth responds to gravity. If I put it on the moon it will run slower, so I have to say it is a machine that measures gravity. My old tick-tock wrist watch has a little spring attached to a wheel and the wheel goes back and forth at a speed that depends on the stiffness of the spring. There is an adjustment inside that lets me adjust the length of the spring (its stiffness), so this machine measures spring stiffness. My old plug-in electric clock has a wheel that spins at a speed determined by the 60-cycles-per-second electricity I get from the power company. If I take it to Europe where they have a 50 Hz electrical supply, it will run at 5/6 the speed, so I have to conclude that this machine counts alternating current electrical cycles. Whatever clock I consider, I find a device measuring or counting something as it occurs and expressing it as time.
It seems that, if a clock measured time, I could put it in the presence of more or less time and it would respond accordingly.
When I put water in my measuring cup and it indicates I have one cup of
water I can understand how the cup measures water. If I use water in my
house, the dials on the water meter spin to measure the water. When I use
more water, they spin more. When I shut off the faucet they stop. I can
understand that this machine is measuring water. But I have to ask, can
you show me a machine that measures time?