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Night Clocks, Italian :
The three Campani brothers, Giuseppe, Matteo and Pietro Tommaso, were, during the 17th century, inventors and first makers of Italian night clocks. The first night clocks were made for Pope Alexander VII, who wanted clocks which made no noise and were softly illuminated at night. The prototypes had rotating drums, run on mercury, like the clock of Alfonso of Castile, but they were soon superseded by conventional 30-hour movements, those of Pietro Tommaso Campani having a particular type of silent escapement in which the pendulum controlled a continuously revolving escape wheel, resulting in a completely silent action. This was an original idea but it was unsatisfactory as far as timekeeping was concerned. Other forms of silent verge escapements were more generally applied. As a rule, cases were in ebonised pearwood in the shape of a baroque altar. The most remarkable characteristic of these clocks was the dial, which was painted copper and looked like an altar piece. The subject of the painting was usually mythological or religious, or of landscapes and flowers. The hours were indicated by means of pierced discs, lit by an internal lamp, which moved along a segmental slit cut into the painting itself. The minutes were shown by the position of the hour disc along the divisions, also pierced, made along the slit. The movements were always well made, some with striking, nearly always spring-driven but sometimes with weights and a system of pulleys to prolong their descent. These night clocks were first made in Rome, and later in other Italian cities.

Nippers :
Cutting tools consisting of a pair of jointed steel levers with hardened cutting edges which close together. They are used for cutting wire, small clock pins, etc., and are shaped as end or side nippers.

Nocturnal :
An instrument for finding the time by night from the position of the two 'pointers' of the Great Bear or Little Bear constellations. It consists of a wooden or metal disc with a handle, marked with an anticlockwise annual calendar scale. Superimposed on this is a smaller disc, pivoted at its center and marked with an hour scale 2 X 12 anticlockwise, carrying an index reading on the date scale or a pair of indexes marked 'GB' or 'LB' for Great or Little Bear. Superimposed again is an index arm projecting well beyond the discs. There is a central hole through the pivot system. To find the time, the observer faces north and sets the date index to the date of use. He then sights the Pole Star through the central hole and rotates the index until it is in line with the pointers of the Great or Little Bear, according to the index employed. The time of night is read off on the 2 X 12 hour scale.

Normande Clock :
A French provincial longcase clock, from Normandy. The clock industry in this area was established in the 17th century. Centers such as Pontfarcy were making 30-hour clocks with short pendulums, but in the course of the 18th century they began to be superceded by Comtoise clock movements, and the individuality of Normande clocks was expressed only in the diversity of case styles. Woods used for Normande cases were oak, chestnut, pine, cherry and occasionally walnut. Shapes were multifarious: some had trunks the same width as the hood, others had swelling enlargements to allow for the swing of the pendulum; there were curved forms, lyre shapes and waisted models. Dials maintained a regional character; some were made in Rouen faience (of which the whole hood might be made in rare instances). Pediments of stamped and pierced brass followed the Comtoise models. Areas within Normandy had their specialties. In Caen and Bayeux waisted cases known as demoiselles were popular. These occurred too in Avranches and Bressey, where violin-shaped cases were also favored.

Novelty Clock :
A small, often animated clock, usually in the shape of a familiar object.

Nut :
The threaded metal block used to secure components with the aid of a screw. By the middle of the 16th century screws had begun to be used by clockmakers and they have been used increasingly since. However, the old wedges or pins continued well into the 20th century.

Nut, Wing :
Nuts with flattened 'ears', allowing easy adjustment by the fingers. They are sometimes found in place of a knurled rating nut at the lower end of a pendulum.

Nutation :
A small oscillation of the Earth's axis of rotation about its mean position, due to the moon's attraction on the Earth's equatorial bulge, superimposed on the slow rotation of the axis round the pole of the ecliptic. It was discovered by James Bradley in 1747 from observations, and amounts to 9.2 seconds of arc, with a period of 18 2/3 years - that of the circuit of the moon's nodes round the ecliptic.