another need a caption, reply, question Take #2

[AlexS]

Thanks . In that case, you're very close.

[RETIRED]

Testing speed of the flow?

[fenderbelly]

Australias' new Collins class submarine on it's initial test run.

[AlexS]

You're all round it . It's calibrating the instrument used to measure flow velocity.
The instrument has a fan that rotates at a rate relative to the velocity, and makes a contact that rings a buzzer every 20 revs.
The bloke at the back pushed the trolley at a range of 'constant' speeds. The bloke sitting on the trolley operated a stopwatch. When they reached constant velocity, he slapped a paintbrush on a survey chain parallel to the tracks and started the stopwatch. At the end of the run, he slapped the paint on again and stopped the watch. Each time the buzzer sounded during the run, he noted the time. On the way back, he calculated the velocity from the paint marks, and wiped off the paint.
They did this for a range of speeds up to as fast as the pusher could go, and then produce a calibration table for the meter, velocity v time for 20 revs.

[RETIRED]

Pity the poor pusher.

[RETIRED]

And thanks Alex.

[fenderbelly]

OK Alex pick a winner i think Bullfright is off again

[pugwash]

As usual, Olly sits down twiddling his necktie while Stan does all the work.

[AlexS]

Go for it Gra, Conex hit the spot.

[Gra]

[Claw Hama]

I wonder if they have twins?

[Lignin]

"I traded it for a pair of leathers"

[tea lady]

Its the only way I can get the b*^$% to sleep.

[fenderbelly]

kid napping

[bullfright]

Dreaming of left turns..................