MASS. By the mass of a body is meant the quantity of matter which it contains, upon the supposition that differences of weight are always the consequence of different quantities of matter. This involves an hypothesis; for instance, if gold be, bulk for bulk, nineteen times as heavy as water, it is presumed that a given bulk of gold contains nineteen times as much matter as the same bulk of water. But it is possible that if we were better acquainted with the constitution of these bodies, it might appear that we are wrong in supposing difference of quantity to be the cause of difference of density.
The. fact is, that mass means weight ; so that of two bodies, the heavier is that which has the more mass : why, then, is this word introduced at all ? If we had only to consider bodies at the surface of the earth, we might in all cases substitute •weights for masses; but when we have occasion to speak of bodies at very different distances from the centre of the earth, their weight towards the earth, which is then called the attraction of the earth, depends upon their distance from the earth, as well as their absolute constitution. If we imagine two planets at the same distance from the earth, the attractions of the earth upon the two will then be in a proportion which depends, not on that distance, but on the amount of matter in the two planets.
When we say that Jupiter has only the 1047th part of the mass of the sun, we express-1, a fact of which observation and deduction make us certain, namely, that at the same distances the attraction of the sun upon the earth is 1047 times as great as that of Jupiter upon the earth ; 2, an hypothesis of the following kind, that the euu contains 1047 times as much matter as Jupiter. The hypothesis is a convenience, not affecting the truth or falsehood of results ; the fact represented remains, that at. the same distances the sun does 1047 times as much towards deflecting the earth as is done by Jupiter.
In the application of mechanics, the following equations frequently occur :— 1Veight = mass x force of gravity. Mass = volume x density.
These equations, like others of the same kind, are to be understood with tacit reference to the units employed ; they spring from the following proportions :—Any two masses are to one another in the ratio compounded of that of the volumes and that of the densities ; thus the two bodies being eight cubic feet three times as dense as water, and seven cubic feet four times as dense, the masses are in the proportion of 8 x 3 to 7 x 4, or of 24 to 28. Again, if two different masses be acted upon by pressures which would, in a unit of time, create different amounts of velocity, the pressures are to one another in the ratio compounded of that of the masses and that of the velo cities which would be generated in the unit of time. Thus if the preceding masses, which are as 24 to 28, were subjected to attractions which would produce in single particles velocities of 10 and 11 feet, if allowed to act uniformly for one second, the pressures requisite to pre vent motion at the outset would be as 24 x 10 to 28 x 11, or as 240 to 308.
To convert these proportions into equations, let the unit of time he one second, that of volume one cubic foot, and let water be the sub stance which has the unit of density ; also let the unit of length be one foot. Then, if the unit of mass be one cubic foot of water, and the unit of weight the pressure necessary to restrain a unit of mass acted on by an attraction which would, in one second, give a velocity of one foot per second, the preceding equations are true. [WEIGHT; SPECIFIO GRAVITY; ACCELERATION.] MASS (Mina, in Latin). The derivation of the word " missa" has been variously accounted for ; some derive it from missio or dimissio, "dismissal," because in the early ages of the church the eatechmneni, or new converts who were not yet admitted to partake of the sacrament', were sent out of the church after the liturgy was read, and before the consecration of the Host. Others derive it from the Hebrew word
" missah," that is, oblation or sacrifice in commemoration of the sacrifice of our Redeemer for the sins of mankind. Ducange, in his Glossarium; art. gives the various opinions on the etymology of the word. The word raises, signifying the ceremony or rite of con secrating the Host, is found in the epistles of St. Ambrose, St. Augustine, and Cesarius, bishop of Arles. See also Baronius, in his Annals.' The mass is a church service which forme an essential part of the ritual of both the Roman Catholic and Greek or Eastern churches, and in which the consecration of the sacramental bread and wine takes place. The canon of the mass now used by Roman Catholics, was first compiled by Pope Gregory the Great, and it was long before it was adopted in all the Latin churches. In the 8th century arose the practice of solitary masses, performed by priests alone in behalf of souls in purga tory, but the practice was condemned by the church at a synod held at Mentz before the end of the century. This service is performed entirely by the officiating priest standing before the altar, and attended by a clerk who says the responses. The prayers of the mass are all in Latin in the Roman Catholic church, in ancient Greek in the Eastern church, and in Syriac among the Maronites and Jacobites, but never in the vulgar or vernacular tongue of the country. The congregation take CO ostensible part in the service, but they follow it mentally or in their in which the text of the prayers is occasionally accom panied by a translation in the vulgar tongue. The priest does not address the congregation, but has his back turned to them, except at the end of certain prayers, when he turns round, and says," Dominus vobiscum" (" The Lord be with you"), and at the "Orate Fratres," &e. ("Brethren, pray," Itc.), which are responded to, on the part of the congregation, by the clerk. The mass consists of various parts : 1. The Introitus, or preparation, consisting of several prayers, psalms, the ` Gloria in excelais; tho epistle and gospel for the day, the Creed, &c., which the priest recites with a loud voice. 2. The consecration, in which the priest consecrates the bread and wine, repeating the words, " Hoc eat corpus meum, et Mc eat calls sanguinis mei; and then shows to the people both the bread and the chalice containing the wine, upon which all the congregation luieel down. 3. The communion. The priest, after reciting more prayers, accompanied by an invocation of the apostles and other saints, the Lord's Prayer, &c., takes the sacrament under both forms ; if any of the congregation are disposed to take the sacrament, the priest then descends from the altar and administers it to them in the shape of the consecrated wafers or bread only. 4. The post communio, which consists of a few more prayers, and of the blessing which the priest gives turning towards the congregation, after which he reads the first chapter of the gospel of St. John down to the fourteenth verse, and the mass is over.
The low or ordinary mass, Mina Luria, lasts in general about half an hour, and every Roman Catholic is bound, by what are styled the "Commandments of the Church," to attend it once at least on Sundays and other holidays, unless prevented by illness. The transgression of this precept is reckoned a sin. Pious persons hear several masses in succession, and many attend mass every day in the week, for it is cele brated every day in each parish church. A priest must not break his fast either by food or drink from the previous midnight until he has said mass, out of respect for the real presence of Jesus Christ in the sacrament The service of the mass is indeed essentially connected with and depends on the doctrine of transubstantiation. [Teaesea