An orchestra today doesn't have to pass on this Symphony because flutes, clarinets, and trombones have to sit it out. These parts, all based on the parts Haydn himself wrote, give those musicians the opportunity to participate in this piece. The timpani part provided here is not the one Haydn wrote; the Vecsey edition even goes so far as to assert no such part exists. If this timpani part is felt to be too modern, it may be more appropriate to take a trumpet part and base the timpani part off that.