DOUBLE BASS (Fr. contrebasse; Ger. Kontrabass, Gross Bass Geige; Ital. contrabasso, violone), the largest member of the modern family of stringed instruments played with a bow, known as the violin family, and the lowest in pitch. The double bass differs slightly in construction from the other members of the family in that it has slanting shoulders (one of the features of the viola da gamba, see Violin); that is to say that where the belly is joined by the neck and finger-board, it has a decided point, whereas in the violin, viola and violoncello, the finger-board is at right-angles to the horizontal part of a wide curve. It is probable that the shoulders of the double bass were made drooping for the sake of additional strength of construction on account of the strain caused by the tension of the strings. The double bass was formerly made with a flat back - another characteristic of the viol family - whereas now the back is as often found arched as flat. The bow is for obvious reasons shorter and stouter than the violin bow.
The technique of the double bass presents certain difficulties inherent in an instrument of such large proportions. The stretches for the fingers are very great, almost double those required for the violoncello, and owing to the thickness of the strings great force is required to press them against the finger-board when they are vibrating. The performer plays standing owing to the great size of the instrument.
The double bass sometimes has three strings tuned in England and Italy in fourths;  in France and Germany to fifths. Owing to the scoring of modern composers, however, it was found necessary to adopt an accordance of four strings in order to obtain the additional lower notes required, although this entails the sacrifice of beauty of tone, the three-stringed instrument being more sonorous. Some orchestras make a compromise dividing the double basses into two equal sections of three and four-stringed basses. The four strings are tuned in fourths: - . Mr A. C. White, finding that an additional lower compass was required, first tuned his double bass with three strings to afterwards adding a fourth string, the lower D. By this accordance the third and fourth strings gain additional power and clearness from the fact that the first and second, being their octaves higher, vibrate in sympathy, obviating the necessity of making the 'cello play in octaves with the double basses to increase the tone when the lowest register is used. In order to obtain equal sonority on his double bass with four strings, Mr White  found it necessary to have a wider bridge measuring about 5 in., so that the distance between the strings should remain the same as on a double bass with three strings, thus allowing plenty of room for vibration. The neck was also widened in proportion. A five-stringed double bass was sometimes used in Germany tuned either to or to but such instruments have been almost superseded by those with four strings. A somewhat larger double bass with five strings by Karl Otho of Leipzig was introduced between 1880 and 1890 with the following accordance: -
The practical compass of the double bass extends from (real sounds) with all chromatic intervals. In order to avoid using numerous ledger lines the music is written an octave higher. The quality of tone is very powerful but somewhat rough, and varies greatly in its gradations. The notes of the lowest register, when played piano, sound weird and sometimes grotesque, and are sometimes used instead of the kettledrum; when played forte the tone is grand and full. The lowest octave is mainly used as a fundamental octave bass to 'cello, bassoon or trombone. The tone of the pizzicato is full and rich owing to the slowness of the vibrations, and it changes character according to the harmonies which lie above it: with a chord of the diminished seventh above it, for instance, the pizzicato sounds like a menace, but with the common chord calm and majestic. Both natural and artificial harmonics are possible on the double bass, the former being the best; but they are seldom used in orchestral works. As an instance of their use may be cited the scene by the Nile at the beginning of the third act of Verdi's Aida, where harmonics are indicated for both 'cellos and double basses.
The technical capabilities of the double bass are necessarily somewhat more limited than those of the violoncello. Quick passages, though possible, are seldom written for it; they cannot sound clear owing to the time required for the strings to vibrate. An excellent effect is produced by what is known as the intermittent tremolo: owing to the elasticity of the bow, it rebounds several times on the strings when a single blow is sharply struck, forming a series of short tremolos. The double bass is the foundation of the whole orchestra and therefore of great importance; it plays the lowest part, often, as its name indicates, only doubling the 'cello part an octave lower. It is only since the beginning of the 19th century that an independent voice has occasionally been allotted to it, as in the Scherzo of Beethoven's Fifth Symphony in C minor: -
These opening bars are played soli by 'cellos and double basses, a daring innovation of Beethoven's which caused quite a consternation at first in musical circles.
The remote origin of the double bass is the same as that of the violin.  It was evolved from the bass viol; whether the transformation took place simultaneously with that of the violin from the treble viol or preceded it, has not been definitely proved, but both Gasparo da Salo and Maggini constructed double basses, which were in great request in the churches. De Salo made one with three strings for St Mark's, Venice, which is still preserved there.  It was Dragonetti's favourite concert instrument, presented to him by the monks of St Mark, and, according to the desire expressed in his will, the instrument was restored after his death to St Mark's, where it is at present preserved. Dragonetti used a straight bow similar to the violoncello bow, held overhand with the hair slanting towards the neck of the instrument; it was introduced into England from Paris, and is a favourite with orchestral players. Praetorius gives an illustration of a sub-bass viol da gamba or gross contra-bass geige  "recently constructed," which displaced the other large contra-bass viols; of which he also gives an illustration. 
Giovanni Bottesini (1822-1889) was the greatest virtuoso on the double bass that the world has ever known. It was not only the perfection of his technique and tone which won him artistic fame, but also the delicacy of his style and his exquisite taste in phrasing.
 The real sounds are an octave lower.
 The Double Bass (Novello, Music Primers, No. 32), p. 6.
 See Kathleen Schlesinger, The Instruments of the Orchestra, Part II. "The Precursors of the Violin Family" (1908-1909).
 See Laurent Grillet, Les Ancêtres du violon et du violoncelle (Paris, 1901), tome ii. p. 159; Willebald Leo von Lustgendorff, Die Geigen und Lautenmacher vom Mittelalter bis zur Gegenwart (Frankfurt a. M., 1904), p. 50; A. C. White, The Double Bass, p. 8.
 M. Praetorius, Syntagma music. (Wolfenbüttel, 1618 and 1620), pp. 54-55 and pl. v. (1).
 Ib. pl. vi. No. 4.
Note - this article incorporates content from Encyclopaedia Britannica, Eleventh Edition, (1910-1911)