Early cornets (1860--1920)
These were generally "shepherd's crook" cornets that were more tightly "wrapped" and are shorter than many later cornets. The sound was gentle, sweet and mellow but not heavy and powerful like a flugelhorn.
The vintage mouthpieces for these instruments could many times today be confused with a french horn mouthpiece. They had very narrow rims with sharp edge drop offs and their bowls were very deep and "V-shaped" like french horn mouthpieces too. Today we call them "cookie cutters," for it looks like you could cut cookies out of dough on a cookie pan with them!
Playing on those cookie cutter mouthpieces can be both frustrating and liberating for players of today! I typically perform on a 1911 Boston "3-Star" cookie cutter mouthpiece. If one uses pressure on this mouthpiece they'll crash and burn quickly. However, if one plays properly without pressure, you can play all night long on one.
Using a shepherd's crook cornet and a vintage-shaped deep "V" mouthpiece produces the most gorgeous, sweet sound you've ever heard. At the peak of the brass band craze at the turn of the 20th century, all the cornet greats played shepard's crook mouthpieces and V-shaped mouthpieces! Today's British Band movement still uses this type instrument and mouthpiece cup shape (but on modern, comfortable rims) and the sound is still mellow and rich.
Keep in mind that the cornet was played in concert for appreciative audiences that were there to listen to music.
Now to it's louder American "brother"
With the jazz age right after WWI came prohibition, underground booze clubs and brothels and the popularity of the cornet in a new type of music that was played in the noisy bars and brothels where people weren't there to listen to music primarily -- they were there to laugh, get crazy, get drunk and... possibly... oh well, you know what I mean!
The bar scene was loud and rowdy, and the sweet, gentle "virgin" of a cornet had to become... well... not as lady-like, sweet or gentle anymore to compete with the crowd noise!
The trumpet at the time was a vulgar-sounding, small bore type horn with a very narrow throated and super long bell that projected only in a lazer-beam ahead of it, and people called 'em "Peashooters." These things were so harsh and edgy and musicians didn't play them much.
NOTE: The "modern" F. Besson "trumpet"--which was much more cornet-like with a wide and faster-flared bell and larger, more cornet-like bore was just taking off and some symphonies were finally replacing their cornets with these F. Besson hybrid cornet-like trumpets. Today the most popular copy of the Besson cornet like "trumpet" is the Bach Strad, and the trumpet is still evolving an sounding better as it moves into even larger, more cornet-like bores and with even wider, faster bell flares like the Wild Thing trumpets use!
Enter the "long model" cornet!
Just as the trumpet was evolving into a more cornet-like instrument in the late teens and 1920's, the cornet was also moving to be more trumpet-like!
In around 1915 Conn invented the Conn "New Wonder" cornet that looked so different from the original shephard's crook "Wonder" model that had been popular for 20 years at the time! The "New Wonder" looked... well, almost like a trumpet, with a trumpet shaped "wrap" and a trumpet shaped long bell, but with a bell flare throat like a cornet that was more mellow than those nasty peashooter trumpet bells. The sound was "almost" like a cornet, but with the projection that was "almost" like a peashooter! suddenly the cornet could be heard over the bar brawl, the lady shouting for another round of booze and the guy trying to pick up the chick!
In 1924 Vincent Bach began making revolutionary mouthpieces too. These had much wider rims that were more rounded in the lip contact area and with deep but rounded "C" shaped cups that were brilliant and cutting but not harsh! Also, and very important for sellers and potential buyers, these rims were so forgiving that even self-taught "lip-mashers" as well as those with less development as players could mash the mouthpiece against the chops and last longer!
By the 1930s most cornets that were made were the "trumpet-bell" type "long models." With traditional funnel-shaped mouthpieces they were still fairly mellow, though not as gentle and mellow as a shepherd's crook cornet with the same funnel mouthpiece.
However, most young band players (like today) wanted to be heard above their band and the "C" shaped cornet mouthpieces made the kid's cornet almost as dominant as if he'd bought one of those newfangled Bach Strad trumpets or Conn 2B or 22B cornet-like trumpets cloned from the F. Besson trumpet!
By the 1960's the poor cornet was (temporarily) dead! Virtually all cornet mouthpieces sold in America were basically trumpet mouthpiece tops on shorter cornet shanks. Plus, some companies made cornets and trumpets that were basically the same instrument except in the leadpipe area where one would be made for a cornet mouthpiece and the other for trumpet. The long model Conn Connstellation cornet/Connstellation Trumpet are a good example. The cornet's model number ended in "A" (like all Conns did then) and the trumpet ended in "B."
The cornet died because, in the end, it couldn't quite project as well as the cornet-like trumpets we now all play. Both instruments had moved towards each other until the gentle cornet sound was heard no more.
Today mouthpiece makers are giving us real cornet mouthpieces, with deep V funnels again and bottoming into bigger diameter throats, but using the modern comfortable rims that we demand today.
In the past, this would have been considered foolish, for the mouthpiece makers of 30 years ago abandoned the better sounding
mouthpiece with designs that weaker kids would buy that had shallower C cups and really tight throats.
Today, the serious player once again is discovering the sweet, human-like and gentle quality that can come out of a shepherd's crook cornet with the proper type funnel mouthpiece! It's not a trumpet... nor is it a fluglehorn... not... it's a cornet!
The blessing and the curse of the "modern" cornet/trumpet/fluglehornmouthpiece rims
In 1924 Vincent Bach began the breakthrough in rim design that we all "benefit" with today. They are wide and round, and very comfortable. They are great when a youngster has to march through a torn-up football field and it's 40 degrees. They are also great for the young player who mashes the mouthpiece against the chops to keep the sound going when tired.
The problem with the modern rim is also it's biggest selling point! You see, when using the brutal, narrow/flat rimmed "cookie cutter" mouthpieces... either you didn't use much pressure, or you died quickly.
Players 100 years ago thus learned not to use pressure. Heck, the pinky finger hook on the leadpipe didn't exist either until the jazz age in order to hold the horn in the right hand only to use mutes or plunger!
Today, when I hit a slump, I pull out the ol' Boston 3-Star cornet (with no pinky ring) and pop in the cookie cutter. Soon... I'm back to great lip trills, improved flexibility and a soaring range that lasts all night, even on the cookie cutter. The slump came because got lazy and wasn't keeping the chops together. When this happens it is easy to let pressure slip in that mashes the poor chops until they swell back together, but flexibility, precision and range suffer and a player slumps!
Modern rims and pinky rings let new players "cheat" and use excess pressure that "helps" them pinch out a note for a few minutes while also greatly sabotaging the chances they will learn to ever play without excess pressure and probably thus never break through that invisible "ceiling" to the next level of playing.