I have only time to add a few words about the percussion instruments which the military band permits to connect with the wind.  Drums are, with the exception of kettle drums, indeterminate instruments, hardly, in themselves, to be regarded as musical, and yet important factors of musical and especially rhythmic effect.  The kettle drum is a caldron, usually of brass or copper, covered with a vellum head bound at the edge round an iron ring, which fits the circle formed by the upper part of the metal body.  Screws working on this ring tune the vellum head, or vibrating membrane as we may call it, by tightening or slackening it, so as to obtain any note of the scale within its compass.  The tonic and dominant are generally required, but other notes are, in some compositions, used; even octaves have been employed.  The use Beethoven made of kettle drums may be regarded among the particular manifestations of his genius.  Two kettle drums may be considered among the regular constituents of the orchestra, but this number has been extended; in one remarkable instance, that of Berlioz in his Requiem, to eight pairs.  According to Mr. Victor de Pontigny, whose article I am much indebted to (in Sir George Grove’s dictionary) upon the drum, the relative diameters, theoretically, for a pair of kettle drums are in the proportion of 30 to 26, bass and tenor; practically the diameter of the drums at the French opera is 29 and 251/4 inches, and of the Crystal Palace band, 28 and 241/4 inches.  In cavalry regiments the drums are slung so as to hang on each side of the drummers horse’s neck.  The best drum sticks are of whalebone, each terminating in a small wooden button covered with sponge.  For the bass drum and side drum I must be content to refer to Mr. Victor de Pontigny’s article, and also for the tambourine, but the Provencal tambourines I have met with have long, narrow sound bodies, and are strung with a few very coarse strings which the player sounds with a hammer.  This instrument is the rhythmic bass and support to the simple galoubet, a cylindrical pipe with two holes in front and one behind, sounded by the same performer.  The English pipe and tabor is a similar combination, also with one player, of such a pipe and a small drum-head tambourine.  Lastly, to conclude percussion instruments, cymbals are round metal plates, consisting of an alloy of copper and tin—­say 80 parts to 20—­with sunk hollow centers, from which the Greek name.  They are not exactly clashed together to elicit their sound, but rubbed across each other in a sliding fashion.  Like the triangle, a steel rod, bent into the form indicated by the name, but open at one corner so as to make it an elastic rod, free at both ends; the object is to add to the orchestral matter luminous crashes, as it were, and dazzling points of light, when extreme brilliancy is required.