Tar Drops, Tear Drops, and Water Drops


“It’s been such a great talking point with colleagues eager to investigate the mechanics of the break, and the viscosity of the pitch.” Shane Bergin Dublin physicist

Mechanics of the break?  Viscosity of the pitch?  Shane?  No, not the Ashes series.  This was Ireland, not England and a really long game, not a mere 5 day cricket match.

Watching tar fall makes watching paint dry instant gratification. It took a biblical life-span to witness the visual aspect of an experimental countdown started in 1944 at Trinity College in Dublin to show the high viscosity of pitch aka bitumen or tar. In the meantime tar babies had become geriatrics-and we’re not talking of the wearers of the green baggy.

Stuff reports* that the pitch-drop experiment, one of the longest-running laboratory investigations in the world, finally captured a drop of tar falling on camera for the first time about 5am Dublin time on July 11 after physicists set up a webcam in April so all comers could try to be the first person ever to witness the drop fall.

A slomo replay was not needed for the scientific finger to be raised after the distillation: it was definitely out. Not quite black velvet* but a moment worth celebrating.

Perfect Pitch?

‘…he’s the reason for the tear drops on my guitar”. Taylor Swift

Tear drops may keep falling on Taylor’s guitar but tar drops are not as swift!*

Bitumen, also known as asphalt and in common parlance, “tar”,  is a sticky, black and highly viscous liquid or semi-solid form of petroleum classed as a pitch. It may be found in natural deposits or it may be a refined product. Bitumen appears solid at room temperature, but it is actually flowing extremely slowly.

What the Stuff story didn’t make entirely clear on first reading was that Irish drops of tar had apparently fallen a long time prior, but just not recorded in real time by a real person. Trees in the quad and all that.

Going against the flow

It turns out that a Downunder version of the experiment was started even earlier in 1927, though with an obvious Irish connection, by Professor Thomas Parnell of the University of Queensland in Brisbane to demonstrate to students that some substances, which appear to be Pinetree solid as, are in fact very high if not hyper viscosity fluids-those that have a property that resists the force tending to cause a fluid to flow. The Irish have long had a fascination with Guiness which also seems to go against the flow.

Parnell poured a heated sample of pitch into a sealed funnel and allowed it to settle for three years. In 1930, the seal at the neck of the funnel was cut, allowing the pitch to start flowing. A glass dome covered the funnel and it was placed on display outside a lecture theatre*. Large droplets formed and fell over a decade.


The eighth drop (it sounds like new Aussie test cricketer Ashton Agar who briefly prised the First Ashes Test door ajar) fell on 28 November 2000, allowing experimenters to calculate that the pitch has a viscosity approximately 230 billion (2.3×1011) times that of water.

Appropriately this is recorded in the in the Guinness World Records as the world’s longest continuously running laboratory experiment. The Queensland experiment was monitored by a webcam but technical problems prevented the November 2000 drop from being recorded.* The Irish experiment won this particular race in a photo finish after hundreds of thousands of internet users had been going with the flow on the Queensland live stream.

It is a wonder the tar experiment hasn’t been interrupted earlier; usually when fresh asphalt is late it is an invitation for another set of contractors to immediately dig it up again.

In October 2005, John Mainstone and the now late Thomas Parnell were awarded the Ig Nobel Prize in Physics for the pitch drop experiment, after it had been controlled for atmospheric conditions.

The rival experiments into viscousness don’t appear to have triggered any academic viciousness; just a bit of donnish sledging.

Raindrops Keep Falling…

In a longer but somewhat less non-scientific experiment, a bet on two raindrops on a window pane which was made 123 years ago has now returned the family of the winner almost £65,000.* The wager was made between an English aristocrat and his friend during a rainy day at a Dorset stately home in 1890. The two men bet £5 on which one of two drops would reach the bottom of the window first.

The disgruntled loser discharged his bet with 4,800 farthings. Still packaged and thus in mint condition 2,794 farthings  dated 1890 recently sold at auction for £63,440, each coin worth almost £23, around 22,000 times its original value, compared with the usual going rate of single farthings  of between commonly command between £2 and £10 at auction. The heirs of the winner were clearly gruntled.

Lucky the two gamblers didn’t bet on two tar drops. Or the glass itself.  Barry Crump’s taxonomy of bastardry Bastards I have Met  has the story of Clive Pepper, a Kiwi old salt and  representative of Bastardus Quaintus, who after 40 years  took all his windows out and turned them around end for end because glass was liquid and the glass at the bottom of the windows was thicker than the glass at the top. He thought inversion would make them last longer.

Queensland Tar Drop Timeline*

The QTD scorecard was somewhat healthier than the Australian card in both innings of the first two Ashes Tests. Though raindrops put the kibosh on an Australian win and a wide open series in terms of where the Ashes end up the third test this week, the Baggies are gathering momentum for number four tomorrow. If you want a bet on a drawn series now is the time to dig out your small change.

Date Event      Duration (years)
1927 Experiment   set up
1930 The stem   was cut
December   1938 1st drop   fell 8.0–8.9
February   1947 2nd drop   fell 8.3
April   1954 3rd drop   fell 7.2
May 1962 4th drop   fell 8.1
August   1970 5th drop   fell 8.3
April   1979 6th drop   fell 8.7
July 1988 7th drop   fell 9.3
28   November 2000 8th drop   fell 12.3

 Postscript: Barry Crump-Going with the flow

I met Barry Crump in 1961, not long after he had Hang on a Minute Mate   published as a follow up to his 1960 bestseller A Good Keen Man.  A friend and I were hitchhiking back from a ski week at Broken River on the way to Arthurs Pass in the Southern Alps. The only vehicle which appeared heading to Christchurch  in well over an hour was a converted bren gun carrier driven by the unmistakeable Barry. He was accompanied by a what appeared to be an underage female Appalachian teenager with flaming red hair. She could have been the etymological source of the disparaging term “crumpet”.

Crump_0_0 A Good Keen Man

In a prequel to his later famous 1980s she’ll be right Toyota ute TV ads* with city slicker Lloyd Scott, Crumpy insisted on driving cross-country every so often before swinging back onto the rough shingle  road.

He also made a point at stopping at every pub the way back to Christchurch. Barry, as expected, quaffed beer and his girlfriend rum and raspberry. One of his just as colourful phrases, with more ice, was “My old man’s so mean he wouldn’t give you the sweat off his balls to make ice-blocks.” We got the picture.

We finally made it to The Square in the Garden City. As it hove into view Russell, who was sitting under the canvas canopy with me in the back, and who only had one kidney, felt a bit sick and stuck his head through the canvas aperture to demonstrate his queasiness in living technicolour.

Unfortunately he didn’t realise that his starting head position was outside the vehicle, where he’d early stuck it to get some fresh air.

For some reason he didn’t make Crump’s 1971 book Bastards I Have Met.


http://www.youtube.com/watch?v=b8J1umP4nBs  Vid  Tar drop 70 years in the making
https://www.youtube.com/watch?v=xKCek6_dB0M  Vid Taylor Swift – Teardrops On My Guitar
http://www.youtube.com/watch?v=8cnzstOtW2k  Vid The DublinersBlack Velvet Band
http://en.wikipedia.org/wiki/Pitch_drop_experiment http://www.dailymail.co.uk/news/article-2373474/Bet-raindrops-stately-home-paid-5-000-farthings-123-years-ago-bears-fruit-descendants-coins-sold-65-000.html 
https://www.youtube.com/watch?v=VILWkqlQLWk  Vid Rain drops keep falling on my head
http://www.youtube.com/watch?v=pyHBKX29_Q8   Vid 
Crumpy and Scotty 1st Toyota Hilux Commercial

#Lyall Lukey  7 August 2013
http://www.lukey.co.nz/  http://www.smartnet.co.nz
http://lukeytraining.wordpress.com/  My other (slightly more) serious blog


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