The time-fuse for boat-guns consists of a brass body having two longitudinal chambers for fuse-composition columns of different times of burning. For the 23-pdr. the times correspond to 1500 and 3000 metres; for the 8-pdr. they correspond to 1100 and 2200 metres. The longer column is always uncapped on loading. The different times are distinguishable by the difference in the caps. That for the long time is of wire; for the short time it is of leather covered with a red wafer. PRIMERS. The primers are of two kinds, percussion and friction. The former seal the vent entirely on firing, and are only used in guns having vents through the breech-block (Model 1870). Friction primers are used in all guns having vertical vents. The percussion primer consists of a body of brass or copper, slightly conical and having a solid head. Into this body screws a small steel anvil carrying an ordinary percussion-cap, which, when the anvil is screwed home, bears against the primer-head. The remainder of the body is filled with fine hunting powder, and the bottom is closed by a shellacked wafer. [Illustration: Quill Primer.] [Illustration: Percussion Primer.] The friction primer consists of two quill tubes, the lower and larger one being filled with fine musket powder, the bottom being sealed with wax. The upper is filled with fulminating composition, and has passing through its centre a brass friction-wire corrugated along its length. The exterior of the wire is formed in a loop for hooking on the firing laniard. The upper part of the primer is closed by a block of wood forming a fairleader for the friction-wire. A small independent loop is attached to the head of the primer, by which it may be withdrawn from the vent without touching the friction-wire. SIGHTS. The sights used in the French Navy are all side-sights, and for the most part the tangent-sights are inclined at a permanent angle. The front-sights are conical in shape, and are screwed into the rim-bases. The tangent-sights are square in section, working in boxes screwed to the face of the breech. They are graduated to full and half cable-lengths (200 and 100 metres). As a rule, guns are sighted on the left side, although provision is made for a right tangent and front sight. Sights are graduated on the left side for shell and on the right for shot, the graduations being all carried across the rear face. In general there is a short and a long sight, the long one being used for distances greater than 30 cables (6000 metres). ACCESSORIES.