PENDANT 



4o5S 



PENDULUM 



is placed on the first. Quantities of these blocks 

 are placed in a press and left to dry under great 

 re. When taken from the press the ends 

 of the blocks are finished; then they are run 

 through a machine with rapidly revolving 

 which cut them into pencils. Pencils of 

 the highest grades are stained and varnished 

 and stamped with the name of the maker and 

 a number or letter indicating the degree of 

 hardness. All the work is done by machinery. 



The leading countries in the manufacture of 

 lead pencils are Germany, England and the 

 United States. All the great pencil factories in 

 America are located in and around New York 

 City. The annual output is valued at about 

 S7 .379.000. It is sufficient to supply the home 

 market and allow the shipping of a large num- 

 ber of pencils to foreign countries, where Ameri- 

 can pencils are highly appreciated. 



Other Pencils. Slate pencils are made of soft 

 slate and may be incased in wood, but most 

 of them are small rods of slate. Colored pen- 

 cils are made by mixing coloring matter with 

 clay or wax and enclosing the pencil in a 

 wooden or a paper case. Pencils for marking 

 on crockery or glass are made of wax colored 

 with lampblack or ivory black. 



PEN 'D ANT, in architecture, an ornament 

 hanging from the ceiling or the pillar of a 

 building. Pendants usually hang from vaults 

 or domes, but in wooden buildings they may 

 hang from the rafters or girders. In some 

 buildings having 

 the roof sup- 

 ported by arches, 

 hang from 

 the arches (see il- 

 lustration). Pen- 

 dants formed a 

 special feature of 

 ancient Oriental 

 architecture, es- 

 pecially that of 

 the Indians, Persians and Saracens, who made 

 them of stone and gave them considerable or- 

 namentation. They were introduced into Eu- 

 rope in the Middle Ages, and fine examples are 

 found in the cathedrals and chapels dating from 

 that period. Those in the chapel of Henry 

 VIII, Westminster Cathedral, London, are 

 among the finest in the world. The pendant is 

 but little used in modern architecture. 



PENDENTIVE, penden'tiv. Cut an orange 

 crosswise through the center and remove the 

 pulp from one of the halves, taking care not 

 to break the peel. Cut a section from the part of 



the peel that forms the top when the rim of the 

 peel n >ts on the table. Mount the part re- 

 maining after cutting off the top in four ver- 

 tical standards, so placed that they will form 

 the corners of a square. Run a thread from 

 the top of each 

 standard to the 

 circle at the top 

 of the orange 

 peel, so placing 

 them as to divide 

 this circle into 

 four equal parts. 

 The triangular 

 segments of the 

 orange peel PENDENTIVES 



, , a , (a) Pendentive. Dotted 



marked oft by lines show completion of su- 

 these threads perstructure. 

 represent what in architecture is called a pen- 

 dentive. That is, a pendentive is the triangular 

 segment of a hemispherical dome formed by 

 arches extending from the four pillars upon 

 which the dome rests to the circumference of 

 the circle formed by cutting off, as it were, the 

 top of the dome. From this smaller circle as 

 a foundation, a second and smaller dome rises. 

 The pendentive is one of the chief characteris- 

 tics of Byzantine architecture, and the finest 

 example of it is in the Mosque of Saint Sophia 

 in Constantinople. See ARCHITECTURE, page 325. 



PEN'DULUM, a weight so suspended as to 

 swing freely in response to the pull of gravity. 

 A bit of metal, suspended from a fixed point 

 by a string and allowed to vibrate, will illus- 

 trate the principle. When Galileo timed the 

 movements of a 

 swinging lamp by 

 his pulse beats 

 and noted that 

 the vibrations 

 were made in 

 equal time, he 

 discovered a fact 

 of great practical 

 value, which re- 

 sulted later in the 

 making of clocks. 



The m ove- 

 ments of the pen- 

 dulum to and fro 

 are called vibra- 

 lions, or oscilla- 

 tions, and the 

 path it traverses is called the arc. The time 

 occupied in passing over this arc is the period, 

 or time, of oscillation. The angle measured by 



FIG 



