John Lloyd was one of the users of post horn in the 1900s. The cornet was invented by adding valves to the post horn around 1828. This shape was largely influenced by the post horn. The post horn is included in Unicode as . The cornet was developed from the post horn through the addition of valves. The second trio of the second minuet features a solo for the post horn. Mahler and others incorporated the post horn into their orchestras for certain pieces. Mozart composed his Serenade No. 9, the "Post horn Serenade", in 1779. A post horn will have a slide for tuning if intended for orchestral settings. The post horn is used in the logo of national post services of many countries. The post horn ("also" post-horn) is a valveless cylindrical brass instrument with a cupped mouthpiece.