Musicians and dancers from Borso’s Bible.

The familiar shape of the slide trombone has been around at least since 1490. That’s when Filippino Lippi included an image of it in frescos he painted at Santa Maria sopra Minerva in Rome.

It hasn’t been around as long as the word “trombone,” which first appeared in 1439 in court records in Ferrara. The court at Ferrara had a three-piece wind band for most of the century. Pietro Agostino played played trombone in that band from at least 1456 to at least 1503.

One of the dukes, Borso d’Este, commissioned a lavishly illustrated Bible, which produced between 1455 and 1461. It includes a picture of a wind band that may well be Borso’s own. At any rate it’s one just like it.

The picture of the trombone doesn’t look anything like the modern trombone. It’s that S-shaped thing on the far right. That form is just one step in a long evolution.

The medieval trumpet

Trumpets of one kind or another have been around almost forever. They existed in the Roman Empire and remained in use in Europe after the collapse of the western part of the empire.

But the most convenient place to start looking at the prehistory of the trombone is during the Crusades. The Saracens, as Arabs were then known, had a different kind of trumpet that they used in battle.

The ancient Romans knew how to bend a brass tube. By the Middle Ages, the technique had been forgotten. I don’t know whether the Saracens knew how to do it, but their war trumpets were straight.

By the 14th century, trumpets 4 feet long and 6 feet long were in common use. Archeologists in 1984 found a perfectly preserved 4-foot specimen at the former location of Billingsgate Lorry Park in London. It was made in four sections that could be easily disassembled for traveling. Surely the longer trumpets were also made in sections.

Beyond the straight trumpet

Can you imagine a holding a 6-foot brass tube in playing position? Can you imagine how glad trumpeters were in the 1370s after someone figured out how to bend a tube?

It’s impossible to bend a hollow tube without cracking it. But if you fill it with lead—or some other solid substance with a lower melting temperature than brass—it’s possible to heat it and bend it a little. Hammer it so the brass is about the same thickness all around again and then bend it some more.

So bending one of the sections of a trumpet made a U-shaped instrument with the same sounding length as a straight trumpet, but only half as long to hold. Of course, that meant that the bell pointed back over the player’s shoulder.

Once instrument makers could bend tubes, however, the solution to that problem was obvious: bend two sections of tubing so the bell points forward again. They already knew how to make trumpets in sections, so they could make short bent sections and attach them to ordinary straight tubes, the last of which would have the bell.

Pictures and other artworks of the time show two different ways of making trumpets with this double bend. One is an S-shaped trumpet comparable to the trombone in Borso’s Bible.

That’s not a very stable shape, and the longer trumpets must have broken frequently—and, of course at the most inopportune times.

Again the solution was obvious and quick in coming: twist the tubing after the second bend so that it lies right next to the tubing before the first bend. The player could hold both of those sections at once. Soon enough, someone decided to bind the two together with a cord.

At last, the slide

But look at the illustration in Borso’s Bible again. Agostino, if it is Agostino, is holding the curvy part at arm’s length. There is no way to prove from a picture that it had a movable slide, but that’s certainly what it looks like.

The first appearance of the word “trombone” in court documents uses it as a vernacular translation of the Latin tuba ductilis. In 1511, Sebastian Virdung wrote the very first book devoted to musical instruments and quoted from a Psalm where that phrase appears. He translated it as “zehenden Busaune,” or “sliding trombone.”

A slide is made by inserting one tube inside a slightly larger one. One tube or the other is made to be stationary, and the other can move back and forth along it. As long as it wasn’t required to play anything very fast, a single slide in the part of the instrument before the first bend can play all the notes necessary for the kinds of melodies played in the 15th century.

The occurrence of “trombone” in Ferrara’s court records does not show the invention of a new instrument. Borso’s father had received a set of trumpets from the Duke of Burgundy in 1420. They were so strange, that he had to ask his benefactor to send him someone who knew how to play them.

By no later than 1410, it appears, the court of Burgundy had what we would now call slide trumpets. Some time after their arrival in Ferrara, they acquired the name “trombone.”

Some time after 1460, when Borso’s Bible was completed, and 1490, when Lippi painted an angel playing something very different, the modern trombone was born.  Just as someone discovered that two bends are better than one for a trumpet, someone else discovered slides with two tubes were better than one.

All it took to make it work was to connect the two outer tubes with a section of bent tubing. It must have been a lot easier to play when it wasn’t necessary to move the entire instrument. Plus, it wasn’t such a long reach to get the lowest notes.