Links!

[nev]

No not hyperlinks.
Or sausages.
Or a type of golf course.
Or cash machines.

But something I just found on the reverse side of an old tape measure I found in the dark cobwebby recesses of the garage clear out.

A link is exactly 66⁄100 of a foot, or exactly 7.92 inches. Apparently

Not really one for keeping things for the sake of it but this just feels nice in the hand and looks good too, though I don't think I'll ever need the reverse side

 

[AndyT]

It's a nice thing in so many ways, even if you don't use it. There's that lovely stiff stitched leather, like a cricket ball. The neat folding brass handle. And the perfectly simple system of units, where if you had an actual metal chain, not a tape measure, it would have a hundred links, each one link long. And ten chains would make a furlong - all nice and simple!

 

[Woody2Shoes]

I don't think I'll ever need the reverse side

Unless you're marking out cricket pitches I guess!

I think that Acres, Rods and Perches (like pounds shillings and pence but for land area) are also based on the "chain" which all good surveyors carried once upon a time.

What a fun object to own!

Cheers, W2S

 

[Billy Flitch]

The measurment `chain` is also the reason that the young man working with a surveyer is also known as the chain lad.
Who knows Nev, maybe in a ealeir life you where a chain lad thats why it feels so good?

 

[nev]

Generally the only chains I encounter are covered in oil

 

[Phil Pascoe]

When I was not long working I was a chain boy for a while. I have an exercise book somewhere from when I was about eight or nine (early sixties) with workings in pounds, shillings, pence and farthings ; distances in miles, furlongs, chains, perches, yards feet, and inches; weights in hundredweights, quarters, stones, pounds and ounces; volumes in bushels, pecks, and gallons; and liquids in gallons, quarts, pints and gills (and to complicate, fluid ounces). I remember always buying potatoes in gallons. Spirit measures were a sixth of a gill - 24 to the pint - except for brandy, which was a supposed to have been accidentally missed off the 1963 weights and measures act. I saw brandy sold in pubs on Dartmoor when I was 16 - 17 (already working in licensed trade, so watchful) in sevenths of a gill so it could be sold at the same price as other spirits. Scotland used fifth gills, just to further complicate.

I wonder why the 66/100ths? 7.92"? if there was a need to use a unit around that size why not 8"? Nice little tape, though - a few years ago before a house move I chucked one away very similar that belonged to a surveyor that worked for my father about 60 years ago, I didn't think to look at it.

 

[AndyT]

I wonder why the 66/100ths? 7.92"? if there was a need to use a unit around that size why not 8"? Nice little tape, though - a few years ago before a house move I chucked one away very similar that belonged to a surveyor that worked for my father about 60 years ago, I didn't think to look at it.

It's because the starting unit was the furlong, which is a useful unit in land surveying since it relates directly to the mile and the acre.
With that as your starting point you need a handy integer to divide the furlong by, so you can make a chain with a sensible number of links, all the same size. The fact that the answer is close to 8" is irrelevant - you don't use inches in land surveying.

What you get is a nice compromise, so the finished chain is big enough to be useful but not too heavy for a smart lad to carry. The links are short enough to allow for flexibility and bundling up, but few enough to be countable efficiently. I expect you remember the intermediate tags so you didn't need to count many individual links.

 

[Phil Pascoe]

I didn't think about that much. They could have had 6" links and had 132 instead of 100 to the chain, I didn't realise they were going metric so early.

 

[Cheshirechappie]

I don't know whether it's true or not, but from somewhere in the dim and distant past I recall learning that a 'pole' (measurement of length, 5 1/2 yards) was taken from the pole used by the driver of an ox plough team to 'encourage' his beasts. Four poles made a chain, and ten chains a furlong - 'furrow long'. The area of land one furlong in length by one chain in width enclosed one acre, which was the area an ox plough team could plough in one day. The invention of the 400HP tractor and six-furrow reversible plough may have made those measurements somewhat obsolete.

Rummaging in the archives, I came up with a 1970s catalogue by RCF tools, who were wholesalers of that era. They list surveyor's chains (by Rabone Chesterman). They offered two lengths, 20m and 30m, tallied every metre, in accordance with BS4484 of 1969 - so the 'chain' as an official length designation had gone by then.

Edit to add - there must have been a reason, now lost in the mists of time, why cricket pitches were one chain (22 yards) long. I doubt it was anything to do with ploughing the outfield with an ox-team, though.

 

[Phil Pascoe]

This one always amuses me -

The Space Shuttle and the Horse's Rear End



Did you know that the US Standard railroad gauge (distance between the rails) is 4 feet, 8 1/2 inches.

That's an exceedingly odd number. Why was that gauge used?

Because that's the way they built them in England, and the US railroads were built by English expatriates.

I see, but why did the English build them like that?

Because the first railway lines were built by the same people who built the pre-railroad tramways, and that's the gauge they used.

Well, why did they use that gauge in England?

Because the people who built the tramways used the same jigs and tools that they used for building wagons, which used that wheel spacing.

Okay! Why did their wagons use that odd wheel spacing?

Because, if they tried to use any other spacing the wagon wheels would break on some of the old, long distance roads. Because that's the spacing of the old wheel ruts.

So who built these old rutted roads?

The first long distance roads in Europe were built by Imperial Rome for the benefit of their legions. The Roman roads have been used ever since.

And the ruts?

The original ruts, which everyone else had to match for fear of destroying their wagons, were first made by the wheels of Roman war chariots. Since the chariots were made for or by Imperial Rome they were all alike in the matter of wheel spacing.

Thus, we have the answer to the original question. The United States standard railroad gauge of 4 feet, 8 1/2 inches derives from the original specification for an Imperial Roman army war chariot.

And the motto of the story is Specifications and bureaucracies live forever.

So, the next time you are handed a specification and wonder what horse's ass came up with it, you may be exactly right. Because the Imperial Roman chariots were made to be just wide enough to accommodate the back-ends of two war-horses.

So, just what does this have to do with the exploration of space?

Well, there's an interesting extension of the story about railroad gauge and horses' behinds. When we see a Space Shuttle sitting on the launch pad, there are two big booster rockets attached to the sides of the main fuel tank. These are the solid rocket boosters, or SRBs. The SRBs are made by Thiokol at a factory in Utah. The engineers who designed the SRBs might have preferred to make them a bit fatter, but the SRBs had to be shipped by train from the factory to the launch site.

The railroad from the factory runs through a tunnel in the mountains. The SRBs had to fit through that tunnel. The tunnel is slightly wider than a railroad track, and the railroad track is about as wide as two horses' behinds.

So a major design feature of what is arguably the world's most advanced transportation system was originally determined by the width of a horse's ass.

 

[swb58]

What a whacky system of measurement. But those units remind me of the wooden 12" rules at school which had all such info printed on them, Rod Pole or Perch - those were the days!
I think the only time I've heard mention of one of them (apart from cricket) is in Australian countryside where a fence has to be not less than a distance of 1 Chain from the roadside to facilitate easy movement of stock.

 

[SammyQ]

Phil.p?

Florins? Half-crowns? Hogsheads? Ahhh...memories!

Sam, who clearly remembers two channels, large choccy bars at 3d and cinema entrance for 6d.

 

[DTR]

This one always amuses me -

The Space Shuttle and the Horse's Rear End



Did you know that the US Standard railroad gauge (distance between the rails) is 4 feet, 8 1/2 inches..........

Just to take it back to where we started, I believe some distances on the railway are still measured in chains!

 

[Phil Pascoe]

6d cinema entry? It used to cost six of us a penny each ... to pay for the guy who went in first and opened the fire exit.

 

[Cheshirechappie]

This one always amuses me -

The Space Shuttle and the Horse's Rear End



Did you know that the US Standard railroad gauge (distance between the rails) is 4 feet, 8 1/2 inches..........

Just to take it back to where we started, I believe some distances on the railway are still measured in chains!

Well - sort of. All new work is done in metric, and has been for at least three decades, but the infrastructure has in some cases been there for 150 years or more, so the old drawings use the old measurements. Thus, railway civil engineers have to be familiar with chains, feet and inches.

I think the heritage railways use a glorious mixture of all sorts of measurements. If it fits, it'll do.....

 

[SammyQ]

6d cinema entry? It used to cost six of us a penny each ... to pay for the guy who went in first and opened the fire exit.

You guys did that one too? We used to have two big strapping bouncers as cinema ushers for that and other rowdy reasons. If you lick black Midget Gems, then catapult them at the screen, they stick...then there was the circular scorch mark on the rear of your Levi jeans....feet up on the seat in front, poise unlit lighter low down in one hand, squeeeeeze....

Sam - who knows at least one unfortunate victim of 'blowback'....