Tuba after American bandmaster John Philip Sousa, resembles a hélicon with the bell pointed up (in the original models as the J. W. Pepper prototype and Sousa's concert instruments) and then curved to point forward (as developed by Conn and others). Some ancestors of the tuba, such as the military "bombardon", had unusual valve and bore arrangements compared to modern tubas. During the American Civil War, most brass bands used a branch of the brass family known as "saxhorns", which, by today's standards, have a narrower bore taper than tuba—the same as true cornets and baritones, but distinct from trumpets, euphoniums,
Brass instrument almost universal by (at latest) 1864 as witnessed by Arban's Method published in that year. The effect of a particular combination of valves may be seen in the table below. This table is correct for the core 3-valve layout on almost any modern valved brass instrument. The most common four-valve layout is a superset of the well-established 3-valve layout and is noted in the table, despite the exposition of four-valve and also five-valve systems (the latter used on the tuba) being incomplete in this article. Since valves "lower" the pitch, a valve that makes a pitch too low (flat) creates