What's the origin of the term "tension" in the context of voltage?

Question

As in a high-tension wire on a utility pole - it's not that it's stretched any tighter than normal, it's just carrying a high voltage.  

I can't think of any way that "tension" would have become synonymous with voltage.  Maybe the visualization of electromotive force pulling charge through a conductor?  I found this: http://www.etymonline.com/index.php?search=tension&searchmode=none which says the use dates to 1802, but nothing further.

I appreciate any insight!

Mr. Smartypants · Accepted Answer

That's what it means, high EMF (electromotive force).  We like to think of voltage as pressure, not tension, but in the old days it wasn't clear whether electricity was pushed or pulled.  In fact people didn't know which way it flowed!  For a long time it was thought to flow from positive to negative, which is why they were called that.  It was only relatively recently that they realized electricity was the flow of electrons, from negative to positive.

I'm surprised the usage of 'tension' in that sense goes back as far as 1802.  It was only a few years before that that we realized electricity 'flowed' at all.  Before that most experiments were with static electricity, not electrical current.

What's the origin of the term "tension" in the context of voltage?

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