Technical description: silver-plated brass; French bell rim. Smooth ball with three gentle undulations. First yard passes through channel in ball; tuning-slide in distal bow, slightly curved to avoid collision with bell. Slide proximal leg has moving outer; distal leg has moving inner; both inner slides have stockings of length 35mm. With adjustable touchpiece for slide operation with ligature restraint, the touchpiece perforated for thread; expansion spring or elastic slide return.With (468a) curved bit and five single-coil crooks for E (468b), E? (468c), D (468d), D? (468e) and C (468f); the three longest crooks have straight sections and a ferrule-covered joint.; Nominal pitch: F etc.; ; ; ; ; Usable pitch: Probably built for use at circa A?=|452.4|Hz (in F with curved bit); probably built for use at circa A?=|440|Hz (in D with curved bit).;
- Specific materials/techniques:
- Decorative elements:
- Inscriptions:Stamped on bell "40|MEDALS OF HONOUR" within banner / monogram|FR / "F.|BESSON / ``Prototype'' / 198|EUSTON ROAD / LONDON" / five-pointed star; below the inscription is an applied metal shield with a blue enamel stag's head in a red enamel background below which in gothic letters "ACN".
- Hornbostel-Sachs category:423.22 Labrosones with slides
- Repository:Royal Conservatoire of Scotland
- Measurements:Overall size: from plane of bell to bow proximal 586; bell 118.; Sounding length: instrument with curved bit but without crooks, minimum (in|F) 1749; with curved bit and D|crook, minimum 2135; overall air column length of curved bit (468a) 107; overall air column lengths of crooks: (468b) 155; (468c) 275; (468d) 395; (468e) 530; (468f) 665.; Bore: curved bit at c|40mm from mouthpiece receiver (minimum bore), 10.35; body at c|15mm from shank/crook receiver (local minimum bore), 10.75; main tuning-slide from 442mm to 725mm from mouthpiece receiver (with curved bit), m.t.s. bore 10.75; slide section from 945mm to 1382mm from mouthpiece receiver, inner slides bore 10.75; at 18.5mm from bell end, 68.B|=|0.79 (in|F), B|=|0.80 (in|D).Bell cutoff |1300|Hz.Dia of mouthpiece receiver of curved bit (468a) 11.6 - 10.6.