I have a copy of a book published in 1844 on "Practical Tunnelling",
written by Frederick Walter Simms. In it he describes the driving of
two tunnels on the railway line to Folkstone. Each tunnel was driven
in segments from a series of shafts along the line of the tunnel, the
rock being hoisted by horse gins. ( As the rock was Greensand, and
very water-bearing, they actually hoisted more water than rock ).
Having many shafts each using a horse whim, Simms thought it a good
opportunity to check on the working rate of the average horse. In the
book he mentions having given a paper the previous year "Upon the
Measurement of Horsepower" to the Institution of Civil Engineers.
So one day I went along to the Civil's library, and asked to see their
proceedings for the year 1843. Simms' general conclusion was that a
horse could work at a rate of 33,000 foot pounds per minute, but if it
did, it tended to drop dead at the end of the shift.
In the ensuing discussion of the paper, one contributor pointed out
that the unit of horsepower was defined by Mr James Watt, who was
in the business of selling steam engines. He sold them on the basis
of "satisfaction or your money back". And, the contibutor added,
"being a Scotsman, he was determined never to have to give any
money back, so defined a horsepower as being a rate of work no
average horse could achieve", thereby ensuring that all his
customers were satisfied regarding the power of his engines.
Tony Brewis
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
|