CABRILLO Historic Structures Report

GLOSSARY

A

AZIMUTH - In plane surveying, a horizontal angle measured clockwise from north meridian to the direction of an object or fixed point. Horizontal direction expressed as the angular distance between the direction of a fixed point (as in the observer's heading) and the direction of the object.

AZIMUTH INSRUMENT or "SCOPE" - A small device similar in size and power to a wildlife spotting scope used for general observations of the sea and for spotting the splash from the projectiles fired from land. An instrument used to measure the azimuth angle.

B

BARBETTE - A mound of earth or a protected platform from which guns fire over a parapet.

BATTERIES - A term with several technical meanings that generally refers to one or more pieces of artillery under the command of a single individual (the battery commander) intended to concentrate their fire on a single target. The term also describes the structures erected for the emplacement, protection, and service of those guns. In the U.S. Army, the term also refers to the artillery corps unit that was the equivalent of an infantry company.

BATTERY COMMANDER'S STATION - The battery commander was in charge of all operations of a particular gun battery. The battery commander's station resembled a fire control station but usually with the addition of several rooms that housed offices, communication gear and plotting equipment and was located near or at the gun battery.

BASE-END STATION - Base-end stations were part of a remote network that tracked targets and relayed data to their associated guns via a plotting room.

BERM - A continuous bank of earth piled against a structure.

BOMB-PROOF - A structure designed to provide security against artillery fire.

BUNKER - A protective embankment or dugout; a fortified chamber mostly below ground often built of reinforced concrete and provided with embrasures. An erroneous term to describe a fire control station.

C

CASEMATE - A bombproof enclosure, generally located under the rampart, to house cannons, which fired through embrasures in the scarp.

CHECK - A small crack running parallel to the grain in wood and across the rings; usually caused by shrinkage during drying.

CORROSION - The deterioration of metal or of concrete by chemical or electrochemical reaction resulting from exposure to weathering, moisture, chemicals or other agents in the environment in which it is placed.

CORROSION STAINING - Surface stains produced by ferrous metal.

CORROSION JACKING - The expansion of ferrous metals during oxidation due to the presence of moisture. The increase in size exerts great pressure, leading to the rupture of the surrounding materials.

CRACK - A building defect consisting of fissures in a material of random width and length.

D

DEPRESSION POSITION FINDER (DPF) or "RANGE FINDER" - A large telescope with a powerful magnification up to 30x used to fix an extremely precise azimuth bearing on a target and measure the angle of depression looking down towards the target. This vertical angle could also be used to calculate the range (or elevation) of the target. The azimuth of the target is the angular distance measured along the horizon from true north (read as zero degrees) to the east (clockwise direction) to the location of the target.

E

EFFLORESCENCE - An encrustation of soluble salts, commonly white, deposited on the surface of stone, brick, plaster, or mortar; usually caused by free alkalies leached from mortar or adjacent concrete as moisture moves through it.

EMBRASURE - An opening with sides flaring outward in a wall or parapet of a fortification usually for allowing the firing of cannon.

EMPLACEMENT - The gun platform, parapet, and accessories.

ENDICOTT - In 1885, President Grover Cleveland assembled a special joint Army-Navy-civilian Board headed by his first Secretary of War, William C. Endicott, to review and submit recommendations for a coast defense program based upon newly developed weapons, particularly the 8-, 10-, and 12-inch caliber guns, and the disappearing carriage.

EROSION - Loss of surface material caused by the abrasive action of elements such as wind, rain, salt or air spray.

F

FERROUS METAL - Metal in which iron is the principle element.

FERROUS STAINING - Staining of a surface due to the oxidation of ferrous metal adjacent to, or embedded in the stained material.

FIRE CONTROL STATION or "BASE-END STATION" -Typically a small, split-level room constructed of steel reinforced, hardened concrete with walls over one foot thick that housed two spotting scopes- the azimuth and the depression position finder. Two to four soldiers were stationed there usually days or weeks at a time and had two basic duties-to watch for enemy ships and track assigned targets.

G

GALVANIZED METAL - To coat steel or iron with zinc to prevent rusting.

GARRISON - A body of troops stationed in a fort.

H

HYDROSTATIC PRESSURE - The pressure equivalent to that exerted on a surface by a column of water of a given height.

I

INCIPIENT SPALLS - Portions of loose material which have not yet detached from the remainder of the material.

J

K

L

M

MAGAZINE - A place for the storage of gunpowder, arms or goods.

MECHANICAL BREAKDOWN - The physical deterioration of a material caused by abrasion, fatigue, creep, fire, overloading or connection failure.

MORTARS - A muzzle-loading cannon with a short barrel in relation to its caliber capable of firing projectiles with low muzzle velocities at high angles; any of several similar firing devices.

N

O

P

PANAMA MOUNT - A concrete ring about forty feet in diameter with a narrow gauge rail embedded on the top in which the trails of a gun were set to allow for a 360 degree rotation of the gun.

PARAPET - A low guarding wall at any point of sudden drop, as at the edge of at terrace, roof, battlement, balcony, etc. A defense wall.

PRESERVATION - Applying measures necessary to sustain the existing form, integrity, and material of a historic property. Deterioration caused by natural forces and normal use are arrested and retarded. Maintenance and stabilization of the material are means to preserve the structure.

Q

R

RECONSTRUCTION - Depicting, by means of new construction, the form, features, and detailing of a non-surviving structure to replicate its appearance at a specific period of time and in its historic location. Features within the period of significance are preserved and deteriorated features are repaired, or replicated.

REHABILITATION - Defined as the act or process of making possible a compatible use for a property through repair, alterations, and additions while preserving those portions or features which convey its historical, cultural, or architectural values.

REPLICATION - Replication creates an exact copy of an element that is missing or damaged beyond repair.

RESTORATION - Restoration accurately presents the form, features, and character of a historic structure as it appeared at a specific period. It may involve the replication of missing historic features and removal of later features, some having cultural value in themselves.

S

SPALLING - The condition of loss of surface material in patches of varying size. Frequently, exposed reinforcing bars are visible in the spall area.

STABILIZATION - Acting to render an unsafe, damaged or deteriorated property stable while retaining its present form.

SUBSIDENCE - The condition of soil settling or falling.

T

TRAVERSE - To move or turn laterally, swivel or pivot.

U

V

W

X

Y

Z