Meeting of Venn Diagrams and a 115-year-old cricket machine

Engineers at the University of Cambridge have recreated a wooden machine that bowled out an Australian international cricketer in 1909. It was originally designed by the famous mathematician John Venn, who gave his name to the Venn diagram.  Cambridge University’s Hugh Hunt set a challenge to his colleague, Thomas Glenday, to recreate the contraption…

Hugh - We are here in the workshops of the Cambridge University Engineering Department and, just down the road, is Caius College Cambridge. And a fellow, the Senior Fellow of Caius College, Cambridge, was a chap called John Venn.

Chris - Now that's a name that rings a mathematical bell. Venn diagrams?

Hugh - Venn diagrams. Exactly. Now there's a lovely stained glass window in Caius College of a Venn diagram. Turned out that one of his interests was cricket and, back in 1909, he built and patented a cricket ball bowling machine.

Chris - And how did this come to light?

Hugh - Last year was the 100th anniversary of Venn's death. In the interests of finding out things about Venn to celebrate Venn diagrams and mathematics, as you do, you search on the internet. Up came this photograph of this chap, Venn, standing in front of a gizmo, as it turns out, in Cambridge at Fenner's Cricket Ground on the day of an Australia versus England three day test match.

Chris - Did it get to bowl at the Aussies then?

Hugh - Yeah, so the story goes. It was in the newspapers. Victor Trumper, who was an Australian top batsman, failed to hit the ball four times in a row I think it was, and this is a real coup now. It wasn't a particularly fast machine but, boy, it put a lot of spin on it.

Chris - But how did you end up building one? We are standing next to what I presume is a replica.

Hugh - This is a replica of John Venn's machine. The photograph from Fenner's Cricket Ground tells us a lot about what it looked like, and the patents, the diagrams in the patents. But still it was a tough job to figure out how to build it because there were no kind of working drawings. So I went into the workshops at the engineering department and uh I said, "Hey, Thomas, do you want to do this? And he didn't say no."

Chris - And you found this guy. It fell to you to try and recreate something from a hundred years ago. How did you go about it, Thomas?

Thomas - So, the machine consists primarily of a fairly heavy base, and then it has a front and rear frame structure that supports effectively two guide rails. Then, you come to the business end of it, which is the throwing arm. There's a pivot mounted on that bottom platform and an approximately seven foot arm, which is a single piece of timber. Then that piece of timber is suspended between the two frames with the main power elastic. Then, there's a rear elastic that catches the arm and prevents it from going full scale and smashing the end of the machine.

Chris - I'm intrigued though why there is a sort of cup that holds the ball, but on the other side of that cup is the thing that looks a bit like you would throw around with a diabolo stick. What is that?

Thomas - The top of the arm houses the contraption that both holds and releases the ball, but it also has a shaft and two bearings inside that imparts a spin on the ball. That's really the critical part of this machine. The rear section you describe as looking similar to a diabolo effectively acts as a cotton reel. When the machine is cocked, a cord is wrapped around that reel and, as the machine goes through its motion, that cord is effectively ripped which puts a spin onto the bobbin, onto the ball, and the ball's released with significant spin on it.

Chris - When Hugh said it produces hideous amounts of spin, the ball is going to leave really, really spinning. Is that not a bit unfair on poor old Trumper when he tried to hit that?

Hugh - I would say it was unfair on Trumper, but there you go. But I reckon this machine could really reproduce a prodigious Shane Warne leg break: a lot of spin, not hugely fast, and maybe that Gatting ball we could reproduce with this machine.

Chris - Put simply, you load a ball up there into the cup and just pull this thing back a bit like a medieval trebuchet against the elastics, let it go, and it just launches the ball in the direction that the arm swings back against the elastic and puts that spin on it. But is it actually any good?

Hugh - It's a very consistent machine. The ball is gonna pitch in the same place and then you're up to the foibles of the pitch and exactly how the ball lands, which is what real cricket is about.

Chris - But what's the critical thing about making balls spin? Does that really make a difference to how they move?

Hugh - A ball spinning through the air curves around, but when the ball lands on the ground, if it's spinning, it will also grip the ground and move off in a direction depending on which way it's spinning. Both of those things are really important.

Chris:
So it's a two dimensional trick really because it's going to move in the air and probably also as the speed of the ball changes, it's going to move different amounts, but it's when it hits the ground, it's also going to throw the batsman off.

Hugh - Absolutely. So when the ball hits the ground, it can move left or right, but if you've got a bit of top spin on it, it can accelerate onto the bat, or a bit of back spin on it and it can lift up. So spin is a pretty critical parameter.

Chris - Have you had a go Thomas?

Thomas - Have I faced the machine? I haven't.

Chris - You daren’t face your own invention?

Thomas - I've been responsible for operating the machine in a safe fashion. So no, I haven't actually faced it myself.

Chris - Where have you tested it?

Thomas - We've taken it to two events so far. The first event was across the road here in Cambridge, and that was so some of our top Cambridge University players could face it. On Monday this week we took it to the Essex County Cricket ground where they were putting on an event to bring maths to life for young children. And in fact, the older side of the population where some residents of a care home came along. So it was really nice to see that multi-generational interest in something that does bring maths and physics into everyday life that, in this case, is the game of cricket.

Chris - Should we fire it?

Hugh - Let's fire it.

Chris - Do you have to be really strong to clock this thing or is it not too bad? You do have to be strong, don't you? It's taking two massive great blokes to pull this thing back.

Hugh - What we've got is a nice handle here, which we can use to release the mechanism.

Chris - I'm going to let Thomas do it so I can watch and see for people at home. I likened it to a trebuchet earlier and that's basically what we've created now because it's cocked right back against the elastics and locked into position. Thomas is standing here with the cord in his hand.

Hugh - 3, 2, 1.

Chris - We just took out half the engineering department's extraction equipment, I think, with that.

Hugh - It was pretty good.

Chris - It's certainly got some power, Hugh.

Hugh - It has got some power. I think that for people who face this for the first time, certainly back in 1909, would've been completely astonished by this. Because you're used to the idea of watching some lumbering bowler come in and you can see when they're coming: "Oh yeah, here they come, here they are, okay. Ready, set, go.” But this is a little bit like firing a gun or something. You don't know when it's coming. I think that would've been quite hard to deal with.