Page:The New International Encyclopædia 1st ed. v. 13.djvu/269

* MECCA. 241 MECHANICAL POWERS. of holding 35,000 people. (See Kaaba.) A great number of people are attached to the niosquo in some kind of ecclesiastical capacity, as hhatib.s (preachers), Kutibs (scribes), Muf- tis, judicial assessors, nuiezzins, etc. In addi- tion lo this, each section of the Jlohainmedau Avorld lias its representatives in Mecca, who take care of its pilgrims, provide them with lodgings, instruct them in the ceremonies, and the like. Bv the side of the mosque runs the Mas'ali, a street lined by high houses and reaching up to the hills, Safa and Marwah, tlirough which the pilgrims must run seven times. A telegraph line coniU'cts Mecca with .Jiddah on the west and with Taif on the east, where the Meccans spend their summer. The history of ilecca has been an eventful one. Mohanunedan legend holds that it was inhabited by Islunael, whose posterity was supplanted by the lidiiii Jiirhum of Yemen, who in their turn were supplanted by the Khuzii'a, also of Yemen, in the year a.u. 210. Aliout 450 a certain Kus- sai of the Koreish familv, and an ancestor of Mohammed, seized the Kaaba and his family is supposed to reign there to-day. Here ilohammed was l)orn (c. 570). and in the same year the city was menaced by the Abyssinians ('Year of the Elephant'). Its patricians opposed the Prophet, but gave in eight years after he had fled to Medina. Though large sums of money were lavished upon it by successive ^Mohammedan rulers, it was not an easy cit,v to hold. It had its own pretender to the Caliphate in Abdallah- ben-Zolicir. who was besieged in ilecca in 692 by the Caliph al-Hajjaj and finally slain. In 030 it was devastated by the Karmathians. But it always had its own rulers or sherifs, descend- ants of the Propliet through Hasan, son of Ali •. and. though they recognized the supremacy of the Fatimites, Mamelukes, and Turkish sultans, they had a large measure of independence. Since Selini I. (1517) they have ruled in the name of the Turkisli Sultan." In ISO:! the Wahliabis took the city, but were driven out bv Mehemet Ali in 1813. A change in the dynasty of sherifs occurred in 1827. Since 1840 their prestige has gradually diminished, a Wall (Governor) being sent b.v the Porte to offset their power. Though all non-Mohammedans are strietl.y prohibited from visiting the sacred territory.a few Euro- peans have been there (see Hajj, where the literature will also be found). Consult Snouck- Hurgronje. Mekka (The Hague, 1888-89, with atlas), which is the standard work on the sub- ject. MECHAIN, ma'slifix'. Pierre Francois An- DRfi (1744- 1804). A French astronomer, born at Laon. He attracted the attention of Lalande (q.v. ). who secured him a place as Government hydrographer. He still, however, managed to keep up his astronomical studies, and was in 1782 elected to .the Academy. In 1791, when the Government had decided to use the arc of merid- ian between Dunkirk and Barcelona as a basis for the new metric system, he was employed to measure that portion which lies between Rodez and Barcelona. On the completion of this work he resumed his observations at Paris, but. an error having been discovered in his measurements, he returned to Spain to correct it and was there stricken with yellow fever. He ■contributed memoirs on eclipses and the theory of comets to the 1'ransactions of the Academy of Sciences and to the Cuiinaissaiicc du Tentjis, of which he was editor from I7S8 till 1794. MECHANICAL ADVANTAGE. See Me- CIlA.NK.^l. PuWKKS. MECHANICAL ENGINEER. See Engi- neer AND Engineering. MECHANICAL ENGINEERS, American Society of. An association of professional me- chanical engineers, manufacturers, and pro- fessors in technical schools, organized in New Y'ork in 1880 to promote the arts and sciences connected with engineering and mechanical con- struction. There are two meetings yearly: one, the regular meeting, in New York City in December ; the other in some manufacturing city. The society has a considerable member- ship in all civilized countries and has head- quarters in New York City, with a library of over eight thousand volumes. Membersliip in the soeiet.v is carefully guarded, and consists of honorary members, members, associates, and juniors. To be eligible as a member, the candi- date must be not less than thirty years of age, and must be a competent engineer, designer, or constructor, or must have served as a teacher of engineering for more than five years. An asso- ciate must be not less than twenty-six years of age, and must possess the qualifications of a member. A junior must have had considerable engineering experience or must be a graduate of an engineering school. The society is governed by a council consisting of a president, six vice- presidents, nine managers, and a secretary and treasurer. MECHANICAL EQUIVALENT OE HEAT. See Heat. MECHANICAL POWERS - MACHINES. Technieall,v described a machine is a combination of resistant bodies for modifying energy and doing work, the members of which are so ar- ranged that, in operation, the motion of an.y member involves definite, relative, constrained motion of the others. A brief anal.vsis of this definition will help to make it clear. First, a machine must consist of a combination of bodies; thus a lever must have its fulcrum, a screw its nut. a wheel and axle its bearings, and so on with other examples: the simplest machine must have at least two members between which relative motion is possible. Second, the members of a ma- chine must lie resistant in order to transmit force : they generall.v are rigid, but not necessarily so, since flexible belts, chains, or springs may be employed to transmit force under the par- ticular action to which they are adapted. Third, a machine is used to modify energy and perfonn work. This proposition is obvious. The con- ception of a machine involves the conception of some source of energy and a train of mechanism suitably arranged to receive, modify, and appl,y the energ}' derived from this source to the de- sired end. A machine, then, consists of ( 1 ) parts receiving the energy: (2) parts transmit- ting and modifying the energy: and (3) parts performing the required work. Finally, (4) the lelative motions of the members of a machine arc constrained or restricted to certain definite, pre- determined paths in which they must move, if they move at all, relatively. The first two propositions of the definition are equally true of structures (such as a bridge) as of machines,