Established in 1831 by Johann Adam Heckel and Karl Almenrader and went independent in 1838. They collaborated on a Boehm system clarinet in the mid 1840's with Iwan Muller and were soon offering Clarinets, Bassoons, Basshorns, Serpents, Flutes, Piccolos, and Oboes. In 1879 Heckel began lining the wing sections with vulcanized rubber and in 1901 patented the whisper key. Heckel manufacturers Bassoons in batches of seven, fitting the key sets individually to each body section. After the keys are fit (mounted), they are each stamped with the unique number of the bassoon and sent on to be plated. On each section (joint) of Heckel Bassoons you will find a manufacturing number in the form of five "dots" which are usually hidden somewhere beneath the key mechanism. The Boot Section has this number imprinted adjacent to the serial number (remove the Bb key from the Bell Section and examine the area between the two posts). On the Bass Section (long joint) this "number" is usually located beneath the Low B Key. On the Wing Section may be located beneath the 3rd finger Ring Key, between the posts of the C# Key, or under the hinge of the F# Trill Key. (Puchner does the same thing, however they manufacture in batches of 15 and "number" their Bassoons with Roman Numerals) Inconsistencies in the serial number to year of manufacture correlations may be due in part to the fact that numbers were assigned to instruments at the time they were ordered. It is unclear whether or not Heckel manufactured instruments during World War 2. There is an absence of serial numbers in the high 8000's, since they stopped making instruments when the WW2 started, and Heckel was only in the mid 8000's at that time. The 9000 series went into production in 1946.