almanac
calendar of astronomical predictions or related data
backstaff
navigational instrument used to measure the altitude of a celestial body (usually the sun)
balance spring
spiral or helical spring that controls balance wheel
balance wheel
weighted wheel in a clock that rotates back and forth to regulate time in place of a pendulum
bi-metallic strip
device made of two different metals that bends as the temperature changes
binnacle
fixed housing for a ship's compass
cartographer
map-maker
chronometer
maritime or high-precision clock
constellation
group of stars regarded as forming a figure
dead reckoning
navigational technique to establish current position based on earlier position and relevant factors such as speed, direction and current
degree, minute, second
measures of latitude and longitude (1 degree = 60 minutes; 1 minute = 60 seconds)
ecliptic
the sun's apparent annual path through the stars
ephemerides
astronomical almanacs (sing. ephemeris)
equator
circle around the Earth (or other planet) equidistant from the poles
escapement
mechanism to convert a clock's rotational motive power into a regulated oscillating motion
fix
geographical position established usually by astronomical observation
gimbals
pivoted device to keep instruments horizontal at sea
going train
system of gears in a clock to transmit rotational torque from the power source (a spring or a weight) to the escapement
horologist
clock-maker
latitude
distance north or south of the equator
lodestone
naturally magnetic oxide of iron
log
record of events on ship
longitude
distance east or west of a defined meridian (usually Greenwich)
lunar distance
angle between the moon and another celestial body, used with reference to an almanac to establish longitude
meridian
circle around the earth, passing through both poles, at right angles to the equator
pallet
projection transmitting motion from an escapement to a pendulum or balance wheel
parallax
apparent shift in position of an object when observer moves
parallel
circle around the earth parallel to the equator = line of latitude
pendulum
swinging weight that regulates the movement of a clock
pole
one of the two extremities of the axis of rotation of the Earth or other planet
polymath
person of great, varied learning
quadrant, sextant, octant
instruments for measuring the altitude of a celestial body (often the sun) above the horizon
quarterdeck
upper deck near ship's stern traditionally reserved for officers
remontoire
intermediate power source in clock between primary source and escapement to reduce force variation
sidereal
measured by the apparent motion of the stars
transit
apparent passage of a celestial body across the sun or a planet
tropic
north or south parallel marking the limit of the sun's divergence from the equator