What is "compound pier"

Compound \Com"pound\,

1. [OE. compouned, p. p. of compounen. See Compound, v. t.] Composed of two or more elements, ingredients, parts; produced by the union of several ingredients, parts, or things; composite; as, a compound word.

   Compound substances are made up of two or more simple substances.
   --I. Watts.

   Compound addition, subtraction, multiplication, division (Arith.), the addition, subtraction, etc., of compound numbers.

   Compound crystal (Crystallog.), a twin crystal, or one seeming to be made up of two or more crystals combined according to regular laws of composition.

   Compound engine (Mech.), a form of steam engine in which the steam that has been used in a high-pressure cylinder is made to do further service in a larger low-pressure cylinder, sometimes in several larger cylinders, successively.

   Compound ether. (Chem.) See under Ether.

   Compound flower (Bot.), a flower head resembling a single flower, but really composed of several florets inclosed in a common calyxlike involucre, as the sunflower or dandelion.

   Compound fraction. (Math.) See Fraction.

   Compound fracture. See Fracture.

   Compound householder, a householder who compounds or arranges with his landlord that his rates shall be included in his rents. [Eng.]

   Compound interest. See Interest.

   Compound larceny. (Law) See Larceny.

   Compound leaf (Bot.), a leaf having two or more separate blades or leaflets on a common leafstalk.

   Compound microscope. See Microscope.

   Compound motion. See Motion.

   Compound number (Math.), one constructed according to a varying scale of denomination; as, 3 cwt., 1 qr., 5 l

2. ; -- called also denominate number.

   Compound pier (Arch.), a clustered column.

   Compound quantity (Alg.), a quantity composed of two or more simple quantities or terms, connected by the sign + (plus) or - (minus). Thus, a + b - c, and bb - b, are compound quantities.

   Compound radical. (Chem.) See Radical.

   Compound ratio (Math.), the product of two or more ratios; thus ab:cd is a ratio compounded of the simple ratios a:c and b:d.

   Compound rest (Mech.), the tool carriage of an engine lathe.

   Compound screw (Mech.), a screw having on the same axis two or more screws with different pitch (a differential screw), or running in different directions (a right and left screw).

   Compound time (Mus.), that in which two or more simple measures are combined in one; as, 6-8 time is the joining of two measures of 3-8 time.

   Compound word, a word composed of two or more words; specifically, two or more words joined together by a hyphen.

Compound pier or Cluster pier is the architectural term given to a clustered column or pier which consists of a centre mass or newel, to which engaged or semi-detached shafts have been attached, in order to perform (or to suggest the performance of) certain definite structural objects, such as to carry arches of additional orders, or to support the transverse or diagonal ribs of a vault, or the tie-beam of an important roof. In these cases, though performing different functions, the drums of the pier are often cut out of one stone. There are, however, cases where the shafts are detached from the pier and coupled to it by armulets at regular heights, as in the Early English period.

These compound piers can be found commonly in Romanesque cathedrals.