Then the instrument is bent over steam and a slat glued onto the inside curve to fix it. Any remaining lacunae in the kerfs are filled and the curved section is covered with leather. The da caccia is played with a double reed; the sound is very mellow and supple. The oboe da caccia stands in a rather unusual relationship to the rest of the oboe family. It cannot rightly be called the precursor of the English horn (the predominant name in North America and German-speaking countries) or cor anglais (the name used in England and France), as it largely developed at the same time as the English horn. The evolution of the English horn is more complex and less straightforward. The da caccia sounds like none of the other members of the oboe family, and no other instrument may legitimately substitute for it—although the English horn is routinely used for this purpose. After Bach, the oboe da caccia quickly fell out of use. The knowledge of its exact sound and construction was lost, and instruments once believed to be oboes da caccia have proven not to be this instrument at all or to consist only of parts of one. The consensus amongst scholars during the first half of the 20th century was that no known instruments from Bach's time had survived to the present day. Curt Sachs, in his "Real-Lexicon der Musikinstrumente" (1913), for example, included a crude and rather speculative drawing of an oboe da caccia. Interest in the da caccia was revived in the early 1970s, in part due to the ongoing Telefunken Records project to record the complete cantatas of J.S. Bach, conducted by Nikolaus Harnoncourt and Gustav Leonhardt. The "taille", a straight two-key oboe pitched in F, had previously been used for the da caccia parts in period-instrument recordings, with mixed results. It fell to Cary Karp, a curator at the Music Museum in Stockholm, Sweden, to make the discovery that in fact "two" well-preserved (but unplayable) Eichentopf da caccias existed in museums in Scandinavia: one of them in his own museum, and another in a museum in Copenhagen. The results of his research were published in the "Galpin Society Journal" article. Using measurements taken from the two instruments, oboist and instrument maker Paul Hailperin of Zell im Wiesental, Germany made the first modern-day copies, and these were used in the Harnoncourt recording of the "Weihnachtsoratorium" that appeared in late 1973.