Direct experimental evidence of time slowing down for moving clocks is well-known. With the advent of atomic clocks, round trip journeys taken by these clocks on slow moving(compared to light speed) jets show time differences with clocks that have not taken the journey. But is there experimental evidence of length contraction. I am thinking of something like sending a large molecule through a narrow stationary slit. At room temperature(slow speeds) the molecule would not make it through the slit, but if they can be accelerated to ~10% of the speed of light, more of the molecules will go through the slit. In this example I use a molecule since it might be easy to accelerate, but any projectile would do.