Fireworks

Not like the days of my youth where I graduated from sparklers and lady fingers to cherry bombs, M-80s, silver barrels to homemade explosives, communities throughout the country have severely restricted or banned personal use of fireworks. Leave it to the experts and retain your fingers.

Here is a good film presented by the American Chemical Society...

And, here is the transcript from NOVA's "Fireworks!" [January 29th, 2002]...

TEENAGE ONLOOKER: They are loud. They are very emotional.

NARRATOR: On the 4th of July fireworks burst across the skies and bombard our senses.

DAVID MUGAR (Executive Producer, Boston's 4th of July): Fireworks is show business.

NARRATOR: And the biggest show around is put on by the Boston Pops Orchestra and fireworks impresario Steve Pelkey.

STEVE PELKEY (Atlas PyroVision Productions): There are two or three major programs of this world-class caliber and Boston surely is the granddaddy of them all.

NARRATOR: Tonight Pelkey will dazzle the Boston crowd with three and a half tons of explosives, precision-launched with the help of a computer network.

STEVE PELKEY: It will make for an absolutely incredible display.

NARRATOR: But the story of fireworks goes back long before computers. It's a story of fire-breathing dragons, the rise and fall of empires, ancient Chinese alchemy, and centuries-old Italian secrets that are jealously guarded even today.

Fireworks: a blend of ancient science, modern technology and pure imagination. Beginning with a simple black powder, they fill the sky with sound and color, and stir the soul of everyone who watches.

But how do they work their magic?

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NARRATOR: In the year 2000 people all over the world ushered in the millennium with the magic of fireworks. A television audience of 4,000,000,000 around the globe watched as the Eiffel Tower was transformed into a gigantic Roman candle.

Fireworks are one of our most enduring customs, and have moved us for centuries. Each dazzling display depends on a simple technology, a black powder known as gunpowder, an explosive mixture that shoots fireworks into the air and propels bullets from guns.

It was the Chinese who first discovered gunpowder over 1000 years ago. Soon they developed simple pyrotechnics, like firecrackers, which they believed had the power to scare away evil spirits. Marco Polo said these devices made such a dreadful noise that anyone not used to it could easily go into a swoon and even die.

The most important ingredient in gunpowder is the compound potassium nitrate, more commonly known as 'saltpeter.' These naturally-occurring crystals are not explosive on their own, but require the presence of a fuel, like charcoal, to produce a flammable mix.

Ancient alchemists refined the recipe to 75 percent potassium nitrate, 15 percent charcoal and 10 percent sulfur. The ingredients become explosive after they're ground together. This highly volatile black powder gave birth to the science of pyrotechnics and the incredible fireworks we experience today.

London's lavish millenium fireworks were put on by chemist Tom Smith, who demonstrates that gunpowder, or black powder, can have dramatically different effects, depending on how it's processed.

TOM SMITH (Pyrotechnic Consultant): Black powder is a mixture of three components, potassium nitrate, sulfur and charcoal. If you mix them together you end up with a powder in which you can still see the white, yellow and black flecks. Now if we burn that, what happens is it burns relatively slowly.

This is really quite useful for the basis of a lot of firework compositions where you want something to burn slowly enough that you can see it in the air. If it burnt too quickly it would all be over and it would be a pointless firework. So lots of sparks being produced slow, burning lots of gas, lots of smoke.

And if you take that same chemical composition but you grind the potassium nitrate and the charcoal together, add the sulfur, grind it over many hours, press it into cakes, break it up, you end up with a powder the consistency of coarse granulated sugar.

Now when we burn that, the fire can travel both through the grains and between the grains and the whole reaction is very much more quick. This sort of thing is used for making the lifting charges of fireworks, where you want lots of gas in a short space of time.

So if you take the same black powder but compress it into a tube, what we get is, in effect, a little fountain. It only burns on the top surface.

NARRATOR: This same black powder can be compressed into marble-sized balls, called stars. They're used in many of the shells in large-scale displays like Boston's 4th of July celebration. Each star-filled shell is ignited by an electronic match inserted into the lifting charge in its base.

STEVE PELKEY: This is a typical chrysanthemum shell that will be fired during the program. At the base of the shell is a black-powdered lift charge. Once that is ignited, it will propel the shell approximately five or six hundred feet into the air. Then there's a secondary burst that takes place within the ball shell. It will then ignite several hundred small marble-sized stars that will determine the shape, which will be round in symmetry because this is a round shell.

NARRATOR: Round shells can also create waterfalls, ring patterns, strobes, titanium salutes and peonies. Roman candles and fountains come from tubes.

Boston's 4th of July celebration is one of the oldest in the nation. It's renowned for the splendor of its music and fireworks show, which draws a huge crowd to the banks of the Charles River. Many come to the same spot year after year, some even camping out overnight to make sure of a good view. By the end of the day, the crowd will total nearly half a million.

This will be a state-of-the-art display. Thousands of fireworks will be set off from this barge. Steve Pelkey is in charge of making sure all goes off as planned.

STEVE PELKEY: We have approximately three and a half tons of devices that are on this barge right now. They are located in approximately 5700 mortars that will have individual firing commands. Most of our shells are packed in sand and racks that are very precision laid out.

NARRATOR: Pelkey's team spends an entire week wiring up these shells to a computer that is programmed to fire them electronically. It's delicate and risky work. High humidity can make gunpowder useless. Lightning or a stray spark of static electricity can set off one firework or dozens at a time. Anything can happen and Pelkey must always be prepared.

STEVE PELKEY: The latest weather report that we got for Boston's Fourth of July: the approach of a cold front will cause more showers and a few thunderstorms.

Do you know if anybody else needs anything?

NARRATOR: Final checks are under way and weather is only one of Steve's headaches.

STEVE PELKEY: You have to satisfy all the needs of the Coastguard, the Boston Fire Department, the park rangers.

Chance of a shower...

You're dealing with the state police. You're dealing with waterway conditions. All of these agencies need to be notified and kept abreast of everything that is going on. We're just going to fire from the outside for tonight's display.

The festivities may get rained on.

I use a lot of this over the 4th of July holiday.

NARRATOR: The evening begins as fireworks and live music are combined in one of the most popular pieces adopted by the Boston Pops and orchestras across the nation, Tchaikovsky's 1812 Overture.

Ironically, the 1812 was written to celebrate the defeat of Napoleon by Russia and has no connection with American Independence. But audiences don't seem to mind as they relish the combination of fireworks, cannon and church bells.

Keith Lockhart conducts it every year.

KEITH LOCKHART (Conductor, The Boston Pops): Well, you can imagine when you put together powerful gunpowder devices and music, it can be a little bit dangerous. I've had occasions where we've done the 1812 or a similar piece in places where they're not so used to doing it, and a group of Army National Guardsmen have come up and been a little over-eager and have pointed the cannon right at us. And even with blanks in them, the impact and sound set the entire orchestra diving off of their chairs and covering their heads. It can be kind of exciting.

NARRATOR: With the orchestra, artillery, and fireworks all clamoring for attention, getting the cues right can be tricky.

STEVE PELKEY: So the real key element here is, hopefully, that evening that Keith Lockhart doesn't get into a moment where he's really kind of going along bombastically.

KEITH LOCKHART: I have to say most of the problems with that sort of thing are in the hands of the fireworks people.

STEVE PELKEY: Keith will do it at his normal pace as the score is written and doesn't get overzealous.

KEITH LOCKHART: The music is what the music is.

STEVE PELKEY: And everything will go off just right on cue as it's supposed to.

KEITH LOCKHART: Tchaikovsky waits for no man.

CANNON OPERATOR: It actually looks very unorganized, but it is organized chaos.

NARRATOR: The fireworks capital of the U.S. is Newcastle, Pennsylvania, population 30,000. Here, fireworks are made the traditional way, almost entirely by hand.

MAN: Our industries over the years have gone bust, but as long as Zambelli is here we'll always have our boom.

WOMAN: The Zambelli name's probably a household name. You hear that name, you think of fireworks.

NARRATOR: The Zambellis, an Italian-American firework dynasty founded in 1893 when old man Antonio swapped Naples for Newcastle. The firm he founded, Zambelli Internationale, is one of the oldest and largest firework companies in America.

Now at its helm is George Senior, a sprightly 76-year-old, known simply to his friends as Mr. Fireworks.

GEORGE ZAMBELLI, SR. (Zambelli Internationale): They call me Mr. Fireworks, yes, because of...hey I've been at it a long time. I devoted my life to fireworks. I've done nothing else. I wanted to be the best and wanted to be the biggest and this is it.

NARRATOR: Much to the annoyance of their rivals the Zambellis call themselves the first family of fireworks. They stage extravagant displays around the globe from Italy to India.

GEORGE ZAMBELLI, SR.: They're magic and everybody loves to be part of magic. When you see them 'ooh' and 'aah' and then stamping their feet at stadiums and so forth, it makes you feel as though you're accomplishing a great deal.

NARRATOR: When George's father boarded the boat in the old country he brought some Italian magic with him, his secret firework recipes, ancient alchemy refined over generations and passed in code from father to son. To ensure these secrets were never lost, Antonio transcribed them into this slim volume before he died. This little black book locked in the Zambelli safe, is the foundation of their empire.

GEORGE ZAMBELLI, SR.: Oh, that book in the safe? Oh that's everything. That's the bible. It's the recipes. You can't do without those. It's got formulas that belong to us and us only.

NARRATOR: These formulas, the Zambellis' heritage, reflect Italy's special expertise in fireworks that began in the 13th century when Marco Polo and the Crusaders brought back firework recipes from the east.

GEORGE ZAMBELLI, SR.: Well we've done more with it. We've had it the longest. It fit the make-up of the Italian people, namely how they like to dance, the music and so forth, and we brought it off to America and here we are.

HELEN WATANABE (Renaissance Fireworks Expert): The Italian tradition really is the one that sets the pace for everybody else. It does seem to be in the north of Italy in the 14th century that they really began to develop fireworks for pleasure.

NARRATOR: Pyrotechnicans would be commissioned by wealthy princes to create incandescent spectacles at court.

HELEN WATANABE: One of the things that a prince might do to show what a superior being he is, is to light up the night sky, fill the city with light, stage a grand firework demonstration. We're still talking about an age which by and large is pre-scientific and pre-technological, so if somebody has technology at their command, they do assume this almost magical quasi-divine status.

NARRATOR: The Catholic Church used fireworks to bring a touch of officially sanctioned magic to hundreds of Saints' days celebrations. The Renaissance was a time of innovation in pyrotechnics.

Over the next 200 years, the Italians developed prototypes of almost all the basic fireworks we are familiar with. But as late as the 19th century, one challenge still stood between the alchemists and total mastery of their art: color. They could make gold, they could make silver, they could create sparks, but their colors were terrible, weak, insipid, almost non-existent.

Then, in southern Italy in the 1830s, pyrotechnicians made their breakthrough. In the gunpowder recipe they replaced potassium nitrate with potassium chlorate, a more energetic source of oxygen. This sped up the rate of oxygen delivered to the reaction, boosting the temperature of combustion from 1700 degrees Celsius to 2000 degrees. This opened the door to a whole new set of chemicals that burned more fiercely and produced more intense colors.

GEORGE ZAMBELLI, JR. (Zambelli Internationale): The Italian artisans worked with those chemicals, learned to make various color combinations and different effects. They've taken the basic chemicals and made a real science and artistry out of it.

TOM SMITH: The modern firework display is full of color. And you make color by adding metals salts, not metals but metal salts to the composition. So, you know, if you put a piece of copper into a fire you see it glow with a blue flame, and we can do the same. It's the sign of a very good firework-maker is a really good strong blue. And here we've added copper oxychloride to the basic oxidant fuel mix and we get a good blue flame.

Adding strontium salts to the mix makes a red flame. And adding barium to the mix makes a green flame. So with those three, and with other metal salts, we have a whole spectrum of colors that we can use.

NARRATOR: The color spectrum is like a rainbow. The metal salt with the longest wavelength is strontium and appears red. Copper salts have a much shorter wavelength and appear blue. By carefully selecting the compound used, any hue can be achieved. If no salts are added, the fireworks reflect all the colors in the visible spectrum and appear bright white.

Inside each of these buildings Zambelli workers continue to refine the firework recipes first developed by their Italian forebears hundreds of years ago in dingy, Neapolitan basements.

DAVID HUSTON (Pyrotechnician): ...lot of secrets, Italian secrets inside of this shell that you wouldn't even be able to understand. I don't even know if I know them. A lot of it went with the old Italian people but a few of them still know it that are around here today.

NARRATOR: It takes many years of training to become an expert firework maker. Louis Zambelli's decades of experience have earned him the title, "Master Pyrotechnician."

LOUIS ZAMBELLI: I'm going to start making the star mines now. They're going to be red star mines.

NARRATOR: A single burst star mine is a simple device. Lift powder packed in one end propels it into the sky. Brilliant color effects and shapes are created by adding stars to the tube.

LOUIS ZAMBELLI: A good day we make about 640.

NARRATOR: The Zambellis are renowned for their extremely complicated multi-break shells which feature as many as 16 different effects in a single firework. These can only be made by hand by the most experienced craftsman.

A simple two-break shell illustrates how color and sound are combined in one device.

FRANK LOFFREDO (Pyrotechnician): Well this shell here is a cut-away basically of a domestic-type shell and it's a Zambelli pattern basically. In here you'll see little cubes and they are stars. The stars will light up the sky at night. So what happens with this typical shell is it splits here and it breaks off, and then what you have sailing down is this, and you could see, notice the casings flicker. This is flash power-powder. So as this is burning and the stars are—with the bright colors, whether it's red, green, yellow—into the sky. This is dropping at about half a sec...I mean a second and a half later this burns in here and you get the boom, the report.

TOM SMITH: Explosives are explosives. Fireworks are explosives. A firework shell that's being projected up into the air is just like an artillery shell only ours produces lots of color and enjoyment and theirs produces destruction.

NARRATOR: Fireworks have loomed large in warfare since their invention. The first rockets and cannons were little more than large explosive fireworks. During the Renaissance, Europe's first displays were supervised by military men who know how to handle the risky ingredients.

HELEN WATANABE: It's exactly the same specialists who design the artillery for war and who then when peace comes, design the fireworks to celebrate the peace.

NARRATOR: A spark-throwing Green Man figured in a royal procession in 1533, the first recorded use of fireworks in Britain. Such pyrotechnics were identified with black magic and uncanny wizardry. They aroused fear as much as wonder.

HELEN WATANABE: A green man is a figure that goes back, I think, to the middle ages as a sort of representation of nature, of natural man, and you find representations in art and they also use them then as jester-like figures to let off fireworks.

TOM SMITH: The green man was traditionally covered in vegetation to mold into the background and I'm sure was quite frightening if he jumped out and waved his firebrands at you.

NARRATOR: If a single man could cast such a spell, imagine the effect of a full-scale fireworks display.

HELEN WATANABE: People were fascinated by light. People spend most of their lives in the dark and to have the power to create vast quantities of fire was only something that an exceptional individual could do. And then if you add to that the ability to produce sparks, to produce explosions, to produce loud bangs, you've then really got something exceptional.

NARRATOR: During the Elizabethan period pyrotechnic dramas became high entertainment. They were lavish stage productions designed for the upper classes, and a fiery dragon was often the centerpiece.

TOM SMITH: The old displays would tell a story with pictorial elements, big set pieces of castles and dragons, all with fire in appropriate places, flying across the stage.

NARRATOR: The designers of these spectacles would be lured from one city to another by lucrative contracts, like baseball players today.

The type of displays familiar to us now first appeared at London's pleasure gardens in the 1730's. These fashionable new venues served up a menu of bear baiting, horse racing and fireworks to anyone who could afford a ticket.

HELEN WATANABE: I think in the 18th century, the tradition does begin to become more diverse, and then, of course, you have to have slightly cheaper possibilities of doing fireworks. It's not just once, one incredible display for a princely christening or a princely wedding. You're going to be doing this every Friday night between, I don't know, April and September.

NARRATOR: Fireworks have now become much more democratic. Audiences today demand ever more complex and ambitious designs.

HELEN WATANABE: I think modern displays differ because we lay enormous stress on the height of the fireworks, on throwing fireworks very high into the sky, impressing just by the sheer height and size and color of the fireworks.

TOM SMITH: I think people like fireworks because it's all the emotions. It's light. It's sound. It's heat to a certain extent. And it's certainly smell.

CLAIRE JENNINGS: The atmosphere here is fantastic. You can feel the excitement in the crowd. The music, the entertainment, the fire, the noise, just everything is so overwhelming. It's so exciting.

NARRATOR: But Claire is not a typical spectator.

CLAIRE JENNINGS: I can see absolutely nothing. Between three and four percent of people who are registered blind are totally blind like me. Most people do have low vision and can appreciate exciting things like fireworks but I can see absolutely nothing.

I just imagine them as flashing lights of different varying colors. And the description that I've had here today has certainly enhanced my impression of what they must look like in that some of them change color. I'd never imagined that before tonight.

TOM SMITH: Noise is a really important part of a firework display. It's what gives it that emotion, gives you that oomph. What we have is three different types of noise, a screecher, a whistle and a bang. The whistle is just a little bit of composition in the bottom of a tube made from potassium benzoate or potassium salicylate and it oscillates when it burns and produces a wave in the tube, just like an organ pipe.

If you drill a hole down the middle of a whistle, it oscillates irregularly and you get a screecher. And of course if you stop that gas going anywhere by sealing the tube what you get is a bang.

NARRATOR: Back at the Zambelli plant, a bang is George Senior's worst nightmare.

GEORGE ZAMBELLI, SR.: Well, do I, will I, do I wake up at night and worry about...well that, that...you got me stuttering at this point. You're...it disturbs you. It bothers you and it makes you restless, no doubt.

NARRATOR: In recent years, over 20 workers have died in firework plants in the United States.

The Zambellis have to comply with stringent safety regulations. Buildings must be separated by concrete blast walls. Roofs are weakened to ensure any explosion travels upwards rather than outwards. Fireworks must be made the age-old way, by hand. Metal machinery could produce sparks and static electricity could easily ignite an entire building full of explosives.

And accidents do happen. All the people who work here either know someone who's been a victim or have suffered themselves.

FRANK LOFFREDO: I was in an accident in 1986. One of the shells from...that we imported prematurely blew up into the tube and back. Then we had cardboard tubes to be shot out of, and when it did blow up, a cardboard tube come at me and it ripped my arm open. I mean they're beautiful but it's number one thing is safety.

NARRATOR: Here in Pittsburgh, 30 miles away from their factory, a Zambelli team is preparing a show to mark the final game of baseball ever to be played at Three Rivers Stadium.

GEORGE ZAMBELLI, JR.: Tonight's extravaganza is put on for the Pittsburgh Pirates. It's their final weekend series here in Pittsburgh and they've commissioned us to do a spectacular for the closing of their season and their existence here at Three Rivers.

NARRATOR: Pyrotechnicians have favorite firing locations such as rivers and lakes where reflections double the visual impact. Three Rivers stadium presents a perfect viewing gallery, although longer mortars and extra lift powder have to be used to boost shells over its high walls. Tonight, the Zambellis will showcase one of their specialties, a non-stop display that features a rapid barrage of shells set off by computer.

MARIE EVANS (Pyrotechnician): This computer can fire shells a tenth of a second apart. It's pin eight that's bad. It's a very nice system to use. This is an eight-strand phone line. This phone line feeds back to little individual modules that fit on the end of the slats at the end of the firework boxes and this computer sends signals out to each of those modules and tells the modules which shell to fire at what time.

NARRATOR: Once the black powder charge in the bottom of the shell has been ignited it burns extremely quickly. Within 15 milliseconds it generates large amounts of gas, blasting shells into the sky at 300 miles an hour. These fiery bombs usually travel 100 feet vertically for every inch of their diameter, so a 6-inch shell will shoot up to 600 feet before exploding. The same shell might produce a burst of as much as 600 feet across.

GEORGE ZAMBELLI, SR.: It's been the method of firing that's been the biggest change we've had, solid state, now computer, and you can do a lot more with the coordination of music, lasers and so forth.

TOM SMITH: The precision of these items both within the burst of it in a perfect sphere of a shell or the timing of a Roman candle so that if you fire eight of them together they're all going up in perfect synchrony, that's the thing that's really improved.

GEORGE ZAMBELLI, JR.: Years ago when I did displays by hand here at Three Rivers, I would actually light a fuse and rotate a couple of feet away and it would be like firing large guns into the sky. It's a real thrill.

NARRATOR: Three thousand dollars a minute of chrysanthemum shells, peonies, fountains and glitter mines, it's the Pittsburgh Pirates' way of saying goodbye.

In these huge extravaganzas imagination is as crucial an ingredient as technology.

STEVE PELKEY: What we do is we produce pyrotechnic symphonies there. Now during the Great Balls of Fire sequence, quite simply, what we're able to do is really exploit the precision of the technology of using computers. When the song first comes in, there are five or six very key piano keys that are going along. We're trying to duplicate those piano strokes.

For instance, you have a five inch shell that has 3.75 seconds of lift time. So right when we want that shell to appear, 3.75 seconds prior to that burst or that musical moment, the shell is fired, it achieves its altitude and then bursts.

What we're doing is we're trying to create a 150-foot-high 50-foot ball of fire right in the sequence, "ba ba ba ba ba great balls of fire."

That is maximizing the computer technology to really create precision choreographed displays.

NARRATOR: The combination of computers and showmanship has created a cycle of rising expectations. Audiences want a more concentrated burst of thrills.

TOM SMITH: There is an increasing trend for people to use pyrotechnics directly, in street theatre for instance, where they will attach pyrotechnics to themselves or take big fountains or use fireworks in close proximity to both themselves and to the audience. It's good, but it's got to be safe. And I just would hate there to be an accident that was caused by something like that which would reflect badly on the whole of the firework industry.

NARRATOR: Despite the risks, a bizarre new fashion in firework displays is to mix people and pyrotechnics in a haunting ballet of danger and delight. The Elizabethan Green Man is reborn.

This is Seattle, home of Wally Glenn. He's a firework fanatic who has given new life to a mythic character he calls, "Pyroboy."

WALLY GLENN: I think some of the appeal of fireworks that might be due to the fact that Seattle, with the high tech industry, people are looking for an escape. It does have a history of people doing some pretty nutty, wild things for entertainment value or just for fun.

I work as a web designer, designing websites, but what I'm doing is quite compelling and quite interesting because the technology behind it, I find quite fascinating.

My colleagues generally think I'm a nutcase. I think it really can be a handicap at work, so it's something I don't really like to promote too much. But eventually it gets out, so then I get back to being treated like a freak.

NARRATOR: Nutcase or not, Wally devotes hours of preparation to creating his one-minute Pyroboy performance. He uses more than 50 of the most powerful fireworks sold in stores. Wally protects himself with special materials like kevlar and nomex.

Kevlar is the material in bullet-proof vests; race car drivers wear nomex to withstand blazing infernos.

WALLY GLENN: I think most people don't realize how much thought goes into it. I think they just assume it's just some moron strapping on a suit and blowing themselves up. I think about the science involved quite a bit. You have to know your chemicals to create, like, a beautiful green or beautiful blue, but not at the same time spontaneously combust. It's...there's a lot of thought you have to go into to make it look good.

If something goes really wrong we're, we're in trouble. We try to work around that by wearing multiple layers so that way it burns off a layer at a time. We do a big safety check to make sure gloves are going to be adequate, the glasses are working right, because if it isn't I end up with a really bad burn and probably end up on a trauma ward.

I've had a few injuries doing Pyroboy. Nothing really serious but the worst is I burned my neck during a show we did down in South Carolina, because a, a fountain had come dislodged and landed on my neck and it started acting like a blow torch.

I take the risk because I enjoy doing it. I cover my body in pyrotechnics and I blow myself up. And the result, Pyroboy.

A typical crowd if they, if they've never seen it before they will be completely shocked and then they will be cheering and there will be a lot of people just astonished at what's going on.

NARRATOR: Would-be Pyroboys should be warned not to try this at home. Each year more than 8,000 people in the U.S. suffer injuries resulting from the personal use of fireworks. A third of those are caused by illegally obtained fireworks. Burns account for over half the injuries. Even simple sparklers burn at temperatures of over 1000 degrees. Children account for nearly half the victims.

In Lima, Peru, illegal fireworks set off an inferno that killed about 300 people. Dozens of sidewalk firework vendors were packed into narrow streets shortly before New Year's Eve. A single, careless firecracker is thought to have touched off hundreds of others. In seconds victims were incinerated on the street, while others were trapped in blazing cars and buildings. Most victims were burned beyond recognition.

Back in Boston, public safety is taken very seriously. The 4th of July event has never had a major accident in its history.

TOM SMITH: Health and safety's so much more of an issue nowadays. And I remember shows when people, you know, loved being there and felt the impact of these things going off. And you just wouldn't dare do it nowadays because you'd have a lawsuit on your hands immediately.

STEVE PELKEY: When we're setting up a fireworks display of this magnitude one of the things that you have to worry sometimes, of course, is whether you have errant shells that will project toward the crowd.

JOSEPH FLEMING: The regulations that Boston enforces are also the same regulations that the National Fire Protection Association would require. It holds people back 840 feet.

NARRATOR: That's the minimum distance of the firework barge from the audience, based on the height and burst diameter of the shells fired, plus a safety pad.

JOSEPH FLEMING: The reason for that is to protect against two primary hazards. The first would be a tube actually shooting its effect almost like a rocket at the audience. Now it's extremely unlikely that would ever happen from these larger ones cause they're in sand and they're isolated and they're in barrels. It's more likely, although still unlikely, that it might happen from one of the smaller ones that's in the wooden racks. But even with that, we have that margin of error of the extra 2- to 300 feet that we hold the audience back...to protect from that taking place.

NARRATOR: Wind conditions that might blow a shell off course are also factored into the safety zone. If winds are stronger than 20 miles per hour it's just too dangerous and the show stops.

Keeping watch while Boston parties is the UCC, the Unified Command Center, a place with many eyes and ears.

DAVID MUGAR: The Unified Command Center is a new approach to event management in this country. And it's something we're trying here for the first time. It's a room that we've converted into a high-tech room to be able to watch on live screens—almost NASA-like—to able to watch live weather radar; to be able to watch down-links from the state police helicopter that has both television equipment as well as thermal sensing equipment on board; to be able to see what's happening in the crowd. Then we also have television monitors to be able to watch live what's happening on stage; a screen to be able to display the maps of the area. Those people are all in one room at the Unified Command Center and able to communicate directly with one another and then of course to communicate over the two-way radio systems to their various troops in the field.

STEVE PELKEY: Yes? Steve.

NARRATOR: With the live performance of the Boston Pops winding down, the crowd's excitement mounts as they await the climax of the evening's display, a 30-minute firework extravaganza set to music with split-second timing.

DAVID MUGAR: Fireworks is show business. It's something also that I think, emotionally, stirs up all sorts of memories in people because almost every child in America certainly at one point or other goes to a firework show—usually on July 4th.

VOX POX: A lot of the music brought a lot of memories back, and the colors and the sounds and people, and hearing everyone enjoy them.

It's America. It's the 4th of July. It's freedom. It's our country. It's wonderful.

STEVE PELKEY: What you want to do is, right off the bat you want to bring the crowd up, right up to its top. And then you want to bring them down a bit with a very, maybe slow, mellow dramatic song. Then bring them back again three or four minutes later to another high point, and then bring it down again. Maybe about midway through the program you want to give people a sense, "This could perhaps be over." A little midway barrage. You're setting up the impact.

Now all of a sudden the beat kicks in and we're programming in different intensities. Now you're starting some criss-cross effects, picking up that intensity. This grand finale is an absolute one-of-a-kind finale. We've gone for absolute sky saturation. We're saturating the sky from 300 feet in altitude to 800 feet in altitude of aquas, lemons, chartreuse, orange, pink, and really just kind of transforming into a rainbow of different colors.

The most important part of the grand finale is when you're covering every inch of your canvas—which is your sky—that you can possibly get away with. We're responsible for sucking the emotion out of every man, woman and child. If they're not emotionally moved then we just haven't done our job.