760 



PYRAMID PYRAMIDS. 



whose dimensions are not yet known with certainty. 

 It is clenvable parallel with the sides of the rhombic 

 l>rism ; lustre resinous ; colour greenish or yel- 

 lowish-white ; translucent on the edges ; hardness 

 that of arragonite : specific gravity 2.6. When 

 reduced to powder, it phosphoresces with a bluish 

 light. Before the blow-pipe, it first becomes 

 lihu-k, then white, and afterwards intumesces and 

 melts on the edges. With borax, it yields a trans- 

 parent glass. It consists of silex, 56.62 ; magne- 

 sia, 23.38; alumine, 3.38; lime, 5.58; oxide of 

 irou, 0.99 ; protoxide of manganese, 0.99 ; and 

 water, 3.5S ; leaving 6.38 of an unknown bitumin- 

 ous substance, and loss. It comes from Pargas in 

 Finland. 



PYRAMID, in geometry, is a solid having any 

 plane figure for its base, and triangles for its sides, 

 all terminating in one common point or vertex. If 

 the base of the pyramid is a regular figure, the solid 

 is called a regular pyramid, which then takes par- 

 ticular names, according to the number of its sides, 

 as triangular, square, pentagonal, &c., the same as 

 the prism. (See Prism.) If a perpendicular from its 

 vertex falls on the centre of the base, the solid is 

 called a right pyramid, but if not, it is oblique. The 

 principal properties of the pyramid may be stated 

 as follows : 1 . Every pyramid is one third of a 

 prism of equal base and altitude. 2. Pyramids of 

 equal bases and altitudes are equal to each other, 

 whether the figure of their bases be similar or dis- 

 similar. 3. Any section of a pyramid parallel to 

 its base will be similar to the base, and these areas 

 will be to each other as the squares of their distances 

 from the vertex. 4. Pyramids, when their bases 

 are equal, are to each other as their altitudes ; and 

 when their altitudes are equal, they are to each 

 other as their bases ; and when neither their bases 

 nor their altitudes are equal, they are to each other 

 in the compound ratio of their bases and altitudes. 

 The solidity of a pyramid is found by multiplying its 

 base by its perpendicular altitude, and taking one 

 third of the product. Frustum of a pyramid is 

 the solid formed by cutting off the upper part of a 

 pyramid by a section parallel to its base. 



PYRAMIDS, in architecture; colossal structures 

 of the ancient Egyptians. According to Herodotus, 

 this people considered the pyramidal form as an 

 emblem of human life. The broad base was signi- 

 ficant of the beginning, and its termination in a 

 point, of the end, of our existence in the present 

 state; for which reason they made use of this figure 

 in their sepulchres. Some writers derive the word 

 pyramid from xvoos (wheat, grain), and understand 

 by it granaries, such, for instance, as those built by 

 the patriarch Joseph ; others suppose it to come 

 from -rvo (fire), because the fbrm of the pyramid is 

 like an ascending flame. The name is probably 

 derived from an old Egyptian word. Some derive 

 it from piramue, a ray of the sun ; others, from 

 pirama, a high monument The Egyptian pyramids 

 (for similar buildings are found among the Baby- 

 lonians, the Indians and the Mexicans) are large, 

 quadrangular and hollow, having a broad base, 

 contracting gradually towards the top, sometimes 

 terminating in a point, sometimes in a plane surface, 

 generally built of large, though not very hard lime- 

 stones (seldom of brick or of any other kind of stone 

 than limestone), of different heights, usually having 

 a base equal to the height, with the four sides placed 

 so as to face the four cardinal points, two of the 

 sides usually being larger han the other two. Some 

 maintain that they were consecrated to the sun, or 

 some other god ; others, that they served as a kind 

 of gnomon, for astronomical observations ; accord- 

 ing to Diderot, for the preservation and transmission 



of historical information ; according to others, th**? 

 ivere built merely to gratify the vanity and tyranny 

 of kings, or for the celebration of mysteries, or 

 iecret meetings, or for corn magazines, or, finally, 

 and this is the most common opinion of the anci- 

 nts, for sepulchres, structures in burial places, 

 symbolical representations of the world of shades, 

 or as chambers for mummies. Among the most 

 renowned are those of Cheops and Cephrenes. 

 Those now standing, all in Middle Egypt, are 

 divided into five groups, which contain about forty 

 pyramids. The district in which the pyramids 

 stand, begins at Dagshoor, and extends by Sakhara 

 and Memphis, almost to 30 N. lat., about 14,000 

 paces in length, and less in breadth. The group 

 of Gize (in the neighbourhood of the ancient Mem- 

 phis) is the most remarkable. Here is the largest 

 one. Herodotus says that it has been supposed to 

 contain the bones of Cheops, and that another one 

 hard by covers the bones of Cephrenes, his brother 

 and successor. The account of this ancient writer 

 is not improbable, which says that 100,000 men 

 worked without interruption for twenty years, in 

 building this enormous pyramid, and that Cheops 

 became an object of hatred to his people on this ac- 

 count. When Savary visited the pyramids of Gize, 

 he obtained a guard from the governor of the dis- 

 trict, to defend him against the Arabs. He left 

 Gize at one o'clock in the morning, and was soon 

 gladdened by the sight of the two largest pyramids, 

 whose summits were illuminated by the moon. 

 They appeared like rough, craggy peaks, piercing 

 the clouds. At half-past four in the morning, the 

 visitors prepared to enter the great pyramid. They 

 laid aside part of their clothes, and each one took a 

 torch in his hand. They began to descend a long 

 passage, which at last became so narrow that they 

 were obliged to creep on their hands and knees. 

 When they had passed through this passage, they 

 were obliged to ascend in the same way. When 

 they had traversed this second passage, they came 

 to a much more spacious apartment, coated with 

 granite, at one end of which Savary saw an empty 

 marble sarcophagus, made of one piece of stone, 

 but without a lid. Fragments of earthen vessels 

 were scattered over the floor. They next proceeded 

 to a second room, which lay under the one above- 

 mentioned, and was of smaller extent. It contained 

 the entrance to a passage which was filled up with 

 rubbish. They now ascended through this, avoid- 

 ing, not without difficulty, a deep well on the left. 

 When they reached the open air, they were all ex- 

 hausted by the heat, which they had endured in the 

 interior of the pyramids. After having rested them- 

 selves, they ascended the pyramids on the outside. 

 They counted about 200 stone steps, varying from 

 two to four feet in height, and they enjoyed from 

 the summit a most delightful view of the country. 

 The descent was much more laborious. Having 

 reached the ground, they walked round it, and 

 surveyed with astonishment the rough mass, which 

 at a distance appeared smooth and regular. The 

 form of this immense structure does not admit of a 

 very exact measurement ; the estimates which we 

 have can only be considered as approximations. 

 Herodotus gives 800 feet as its height, and says 

 that this is likewise the length of its base on each 

 side. Strabo makes it 625, Diodorus 600. Modern 

 measurements agree most nearly with the latter. 

 The difference of these results may be owing partly 

 to the circumstance of their having been made at 

 different times, and the sand having been higher at 

 one time than another. Strabo says that the stone 

 which closes the entrance to the pyramids, is to be 

 found nearly in the centre of one of the sides ; if 



