Hartley colliery beam question

[tomferry]

Started my new read last night mine ventilation - D & JS Penman cannot understand all the math equations but is still a most interesting read !

I don't know the book, but if you are going to look at ventilation you will find the maths very much easier in metric units. Imperial ventilation units were hard work.
Think of ventilation as like electricity. You have voltage which is pressure pushing the air round, current which is volume moving and resistance which is the resistance of the roadways.

Thank you very much that is most helpful ,  to me it?s a very hard read on the maths side of it but included is so much useful information I can collect about different types of ventilation set ups  it?s most useful  and the gas explanations are the best !