Answer Man

Large locomotive smokestacks solved burning problem

The Great Western Railway was known for its copper-capped chimneys, such as this bizarre stack bent at a 90-degree angle. It was built in 1890.
The Great Western Railway was known for its copper-capped chimneys, such as this bizarre stack bent at a 90-degree angle. It was built in 1890.

Q. On the top of most old locomotives was a relatively massive smokestack through which the exhaust from the engine could escape. Some were sort of diamond-shaped while others looked like huge upright funnels. I’ve always wondered why this chimney or smokestack had to be so big and elaborate.

— Tom Westerheide, of Belleville

A. After seeing countless examples of these in historical TV shows and movies over the years, my initial thought was that it may have been a cosmetic decoration to draw attention and make the engine look distinctive. You know, sort of like someone adding a racing spoiler to her Camry even though she only drives to church on Sunday.

But when I did a little research, I found it wasn’t to make the locomotive look “hot” at all. Rather, it was developed to help keep both the passengers and the surrounding environment from being burned alive. Because if you think modern air travel is hell, you should have ridden an early 19th-century train.

As you might expect, locomotive inventors at first were trying merely to make such mechanical beasts move far enough and fast enough to make them practical. Back then, they had to burn wood or coal to heat water that produced steam to drive the pistons. Nobody worried what happened to the smoke and ash coming from the burning fuel other than designing a rudimentary exhaust system to allow it to escape. As long as the thing kept moving without blowing up, victory had been achieved.

But not for long. Think about it: If you spend any time relaxing in front of a roaring fire, what do you see? In addition to the inviting flames, you likely see burning embers popping off the logs and floating up the flue. Today, that flue is designed such that these sparks won’t set your roof or house ablaze.

On early trains, all bets were off because the developers had not yet taken this potential risk into account. Hence, on Aug. 9, 1831, the Mohawk and Hudson Railroad made its first regular trip between Albany and Schenectady with an engine and three 10-passenger cars fashioned from stagecoaches mounted on trucks. Passengers settled back to enjoy a once-in-a-lifetime experience they’d never forget — and that’s exactly what they got in a way they never expected, according to this excerpt from “The Evolution of the American Locomotive” by Herbert Walker:

“The conductor had a small seat on the rear of the tender and gave the signal for starting by blowing a tin horn. We are told that ‘the fuel used was dry pitch pine, and as there was no spark arrester on the stack, the sparks poured back on the passengers in such a volume that they raised their umbrellas as shields. The covers were soon burned off the umbrellas, and each man whipped his neighbor's clothes to put out the fires started by the hot cinders.’”

It wasn’t just the poor passengers, either. Even as late as 1880, Harvard College professor Charles Sargent reported that the third leading cause of forest fires was passing locomotives. Of the 2,983 recorded fires that year in the United States and Canada, about a sixth — 508 — were caused by trains, according to his “Report on the Forests of North America (Exclusive of Mexico).”

England didn’t have this problem. Their trains ran on coke, which did not produce the sparks. But early on, the United States fell in love with wood, which produced a fireworks display that apparently could set the train itself on fire if the crew was not careful.

Eventually, train manufacturers began developing an effective “spark arrester” — a device that stops flammable debris from escaping a source of combustion such as a locomotive engine.

At first, they simply installed wire screens within the smokestack. But early stacks were relatively small, which meant the screens were, too. This was a problem. As embers collected on the screen, they increasingly blocked the flow of steam, smoke and heat that was trying to escape. As this exhaust built up, the screens melted and the burning embers were free to fly off once more.

You can probably see where this is headed. To adequately control the embers, spark arresters grew in size, which meant the smokestack followed suit. According to John White Jr.’s “A History of the American Locomotive,” the most popular was the “bonnet” chimney. In this design, you had a big funnel-shaped sheet metal cone fitted over an ordinary cylindrical chimney.

Here’s how it worked: The upper portion of the funnel hid an inner cone at the top of the cylindrical chimney. This smaller cone deflected the embers outward against the inner walls of the outer cone. The heaviest embers fell into a collection hopper that was enclosed at the bottom of the funnel. The lighter steam and smoke passed harmlessly through the wire screen that covered the upper, large-diameter end of the funnel to trap any remaining smaller embers. Experts say this deflection and collection of embers in that large cone extended the life of the screen by up to a month.

These stacks became increasingly elaborate in many cases and became known by the names of their developers. Sophisticated designs, such as the Rushton and Radley-Hunter, employed various centrifugal separation baffles in the bonnet. Railroads also came up with distinctive individual variations. In England, the London and South Western Railway featured the William Adams’ Stovepipe chimney on its trains. On this side of the pond, the Great Western Railway was known for its copper-capped chimneys. (For a bizarre stack bent at a 90-degree angle, see http://spec.lib.vt.edu/imagebase/norfolksouthern/full/ns716.jpeg.)

As coal replaced wood, the bonnet was reduced in size to a simple diamond stack that housed the inner deflecting cone but with no collection hopper. Now, with diesel engines and bullet trains, these stacks have died out like the embers they used to emit, seen largely only on heritage railways that take train enthusiasts back to enjoy an earlier era without meeting a fiery end.

Today’s trivia

What member of a famous comedy team was among the first group of players inducted into the Croquet Hall of Fame in 1979?

Answer to Thursday’s trivia: The 600 species of crawdads can be found on every continent except two. Naturally, Antarctica is one. But while you might suspect Australia is the other because of its remoteness, it’s not. It’s Africa for reasons not entirely clear. Some say, like India, conditions became too warm for crawdads to exist after the supercontinent of Pangaea began to break up 175 million years ago. Bonus fact: The name “crayfish” may have evolved from the Old High German “krebiz” and Old French “escrevisse,” meaning “edible crustacean.”

Send your questions to Roger Schlueter, Belleville News-Democrat, 120 S. Illinois St., P.O. Box 427, Belleville, IL 62222-0427, rschlueter@bnd.com or call 618-239-2465.

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