Maelzel's Panharmonicon was a large barrel-operated orchestrion.
The "trumpet" sound was provided by a rank of pipes. Parts of the
Panharmonicon are shown on pp. 131-132 of Dr. Alexander Buchner's book
"Mechanical Musical Instruments" (Batchworth Press, London, undated,
c. 1954). One shows a corner of the interior of the instrument,
including a kettle drum, field drum, triangle, a pair of cymbals and
several ranks of pipes, one of which is probably the trumpet. The
other shows a man standing next to four of the Panharmonicon's pinned
wooden cylinders, which appear to be about four feet long and 10" or
11" in diameter.
According to Buchner, the instrument was in the Industrial Museum in
Stuttgart, where it was destroyed during the second World War.