CON 



of union that prevented the separation of 

 mankind into distinct nations; and some 

 have imagined that the tower of Babel 

 was erected as a kind of fortress, by which 

 the people intended to defend themselves 

 against that separation which Noah had 

 projected. 



CONGE D'ELIRE. The king's per- 

 mission royal to a dean and chapter, in 

 time of a vacation of the see, to choose or 

 elect a bishop. See BISHOP. 



CONGELATION, may be defined the 

 transition of a liquid into a solid state, in 

 consequence of an abstraction of heat : 

 thus metals, oil, water, &c. are said to 

 congeal when they pass from a fluid into 

 a solid state. With regard to fluids, con- 

 gelation and freezing mean the same 

 thing. Water congeals at 32, and there 

 are few liquids that will not congeal, if 

 the temperature be brought sufficiently 

 low. The only difficulty is, to obtain a tem- 

 perature equal to the effect ; hence it has 

 been inferred that fluidity is the conse- 

 quence of caloric. See FLUIDITY. Every 

 particular kind of substance requires a 

 different degree of temperature for its 

 congelation, which affords an obvious 

 reason why particular substances remain 

 always fluid, while others remain always 

 solid, in the common temperature of the 

 atmosphere ; and why others are some- 

 times fluid, and at others solid, according 

 to the vicissitudes of the seasons, and the 

 variety of climates. See COLD, FREEZ- 

 ING. 



CONGREGATION, an assembly of 

 several ecclesiastics united, so as to con- 

 stitute one body ; as an assembly of cardi- 

 nals, in the constitution of the pope's 

 court, met for the dispatch of some par- 

 ticular business. 



CONGREGATION, is likewise used for as- 

 semblies of pious persons, in manner of 

 fraternities. 



CONGREGATIONALISTS, in church 

 history, a sect of protestants who reject 

 all church government, except that of a 

 single congregation. In other matters, 

 they agree with the presbyterians. See 

 PRESBYTERIANS. 



CONGRESS, in political affairs, an as- 

 sembly of commissioners, envoys, depu- 

 ties, &c. from several courts, meeting to 

 concert matters for their common good. 



CONGRUITY, in geometry, is applied 

 to figures, lines, &c. which, being laid 

 upon each other, exactly agree in all 

 their parts, as having the very same di- 

 mensions. 



CONIC sections, as the name imports, 

 are such curve lines as are produced by. 

 the mutual intersection of a plane and 



the surface of a solid cone. The nature 

 and properties of these figures were the 

 subject of an extensive branch of the an- 

 cient geometry, and formed a speculation 

 well suited to the subtle genius of the 

 Greeks. In modern times the conic geo- 

 metry is intimately connected with every 

 part of the higher mathematics and natu- 

 ral philosophy. A knowledge of those 

 discoveries, that do the greatest honourto 

 the last and the present centuries, cannot 

 be attained without a familiar acquaint- 

 ance with the figures that are now to en- 

 gage our attention. 



We are chiefly indebted to the pre- 

 servation of the writings of Apollonius 

 for a knowledge of the theory of the an- 

 cient geometricians concerning the conic 

 sections. Apollonius was born at Perga, 

 a town of Phamphylia, and he is said to 

 have lived under Ptolemy Philopater, 

 about forty years posterior to Archime- 

 des. Besides his great work on the conic 

 sections, he published many smaller trea- 

 tises, relating chiefly to the geometrical 

 analysis, which have all perished. The 

 treatise of Apollonius on the conic sec- 

 tions is written in eight books, and it 

 was esteemed a work of so much merit 

 by his contemporaries, as to procure for 

 its author the title of the great geometri- 

 cian Only the four first books have come 

 down to us in the original Greek. On the 

 revival of learning, the lovers of the ma- 

 thematics had long 1 to regret the original 

 of the four last books In the year 1658, 

 Borelli, passing through Florence, found 

 an Arabic manuscript in the library of 

 the Medici family, which he judged to 

 be a translation of all the eight books of 

 the conies of Apollonius : but on ex- 

 amination, it was found to contain the 

 first seven books only. Two other Ara- 

 bic translations of the conies of Apollo- 

 nius have been discovered by the indus- 

 try of learned men : and as they all 

 agree in the want of the eighth book, 

 we may now regard that part of the 

 treatise as irrecoverably lost. The work 

 of Apollonius contains a very extensive, 

 if not a complete, theory of the conic sec- 

 tions. The best edition of it is that 

 published by Dr. Halley, in 1710 : to 

 which the learned author has added a re- 

 storation of the eighth book, executed 

 with so much ability as to leave little 

 room to regret the original. 



Since the revival of learning, the theory 

 of the conic sections has been much cul- 

 tivated, and is the subject of a great va- 

 riety of ingenious writings. Dr. Wallis, 

 in his treatise " De Sectiombus Conicis," 

 published at Oxford, in 1655, deduced 



