Go ahead, look at the inside of your mouthpiece. If it’s like my Selmer C** bari mouthpiece it has a fairly complex interior. The C** has a round bore through the shank and body that transitions suddenly into a square throat. The inner side walls remain square to the floor all the way out to the tip rail and the floor not only curves up to the baffle but is slightly dished across its width. Then the side rails also curve starting at the breakpoint all the way to the tip rail producing the tip opening. Measuring the volume of this space could be quite challenging.

Remember way back on the first page I said that I was doing all the measurements in the metric system? Here’s the reason – the metric system has a volume/mass equivalent built into it. One cubic centimeter (or milliliter) of water weights 1 gram at 4 degrees Centigrade. While 4C is 39.2F – a bit chilly – water still has a mass of 0.9982 grams per cm at room temperature. Good enough for our use.

By filling the mouthpiece with water then weighing the water we can easily determine the volume of the mouthpiece. This is why everyone in the world uses the metric system . . . except the U.S. Our only brush with the metric system is the 9mm handgun. But I digress.

I just happen to have a precision 10milliliter (10 cubic centimeter) volumetric flask. Don’t ask. Here’s a picture of it with a Rico bari sax reed holder and a quarter next to it for reference. If you fill the flask so that the very bottom of the meniscus just touches the ring inscribed around the neck you’ll have exactly 10 cubic centimeters of fluid (at 20 degrees centigrade of course).

We should verify that my kitchen scale is up to the task. Because what I’m weighing is very light and I don’t know the accuracy of the scale under light loads, I pre-loaded the scale with a book (about 480 gm) then zeroed the scale out.

If we put the flask on the book (on the scale) we get the weight of the flask.

The empty volumetric weighs 10 gm which means if we fill it to the line (10 cubic centimeters) it should weigh 20 gm.

20 gm it is – I love it when a plan comes together! Now let’s measure the volume of my Selmer C** mouthpiece.

Measure here: How Big Is Mine?