Owing to the changes of pitch by crooks, it is not easy to define the compass of the French horn. Between C in the bass clef and G above the treble will represent its serviceable notes. It is better that the first horn should not descend below middle C, or the second rise above the higher E of the treble clef. Four are generally used in modern scores. The place of the horn is with the wood wind band. From Handel, every composer has written for it, and what is known as the small orchestra of string and wood wind bands combined is completed by this beautiful instrument. The most prominent instruments that add to the splendor of the full orchestra are trumpets and trombones. They are really members of one family, as the name trombone--big trumpet--implies, and blend well together. The trumpet is an instrument of court and state functions, and, as the soprano instrument, comes first. It is what is known as an eight foot instrument in pitch, and gives the different harmonics from the third to the twelfth, and even to the sixteenth. It is made of brass, mixed metal, or silver, and is about five feet seven inches in real length, when intended for the key of F without a slide; but is twice turned back upon itself, the first and third lengths lying contiguous, and the second about two inches from them. The diameter is three-eighths of an inch along the cylindrical length; it then widens out for about fifteen inches, to form the bell. When fitted with a slide for transposition--an invention for the trumpet in the last century--this double tubing, about five inches in length on each side, is connected with the second length. It is worked from the center with the second and third fingers of the right band, and, when pulled back, returns to its original position by a spring. There are five crooks. The mouthpiece is hemispherical and convex, and the exact shape of it is of great importance. It has a rim with slightly rounded surface. The diameter of the mouthpiece varies according to the player and the pitch required. With the first crook, or rather shank, and mouthpiece, the length of the trumpet is increased to six feet, and the instrument is then in the key of F. The second shank transposes it to E, the third to E flat, and the fourth to D. The fifth, and largest--two feet one and a half inches long--extends the instrument to eight feet, and lowers the key to C. The slide is used for transposition by a semitone or a whole tone, thus making new fundamentals, and correcting certain notes of the natural harmonic scale, as the seventh, eleventh, and thirteenth, which do not agree with our musical scale. Mr. W. Wyatt has recently taken out a patent for a double-slide trumpet, which possesses a complete chromatic scale. In the required length of slide the ear has always to assist. It is clear that the very short shifts of a double slide demand great nicety of manipulation. It is, of course, different with the valve trumpet.