Page:The New International Encyclopædia 1st ed. v. 13.djvu/172

* MASONRY. 146 MASONS. bent to right angles with tlio body, the bent ends of which enter holes in the upper surfaces of adjacent stones. Ashlar masonry is used for works in which great strength and stability are reiiuired. The stones for ashlar masonry usually have a lengtli of from three to five times the depth, and a breadth of from one and a half to two times the depth. The thickness of the mortar joints in the very best class of ashlar masonry for building purposes is about % inch; for railway and bridge masonry about V4 inch to ',:; inch. The stones are laid so that the vertical joints of one course come ajiproximately over the middle of the stones below, or, technically, the stones 'break joints.' The arrangement of headers and stretchers varies; the strongest arrangement is wlii-re a header and a stretcher are used alter- nately. Dowels and cramps are used where ex- ceptional strength is re(|uiri'd. Pointing is done by .scraping out the mortar to a depth of at least >/i inch from the face of each joint and lilling the void with a high-quality mortar tliorougbly rammed, and sometiuies (inisliing the exposed' edge with a bead. Ashlar masonry is usually backed with rubble masonry, the backing being built simultaneously with the facing. Squared stone masonry is built like ashlar masonry ex- cept that dressed stones are not used and range work is seldom employed; the backing and point- ing are the same as for ashlar masonry. Iluhhle masonry is employed for backing ash- lar, and squared stone masonry is used for small- sized abutments, culverts, small building founda- tion walls, etc. The stones are prepared for laying by simply knocking oil' the weak corners and loose pieces. .VU interstices are filled with small pieces of stone and mortar, and the mortar joints are made thick enough to prevent adjacent stones from Iduchiiig. Very often rubble masonry is laid without mortar, and is then called dry rubble masonry. The strength of stone masonry varies with the strength of the stone, the size of the blocks, the accuracy of the dressing of the joint faces, the proportion of headers to stretchers, and the kind and quality of the mortar used. Prof. I. O. Baker, in .1 Treatise on Masonry Construc- tion (Xew York, 1000), gives the following as a safe load per .square foot on diltVrent kinds of stone masonry: Rubble, 10 to 1:3 tons; squared stone. 15 to 20 tons; limestone ashlar, 20 to 25 tons; granite ashlar. .30 tons. In cer- tain classes of stone masonry, such as arch bridges and lighthouses, the stones are cut to exact dimensions and to special forms. In light- house construction these special forms are sonie- tiniiv quite intricate. (See LuiiiriiorsE. ) In building ma>iinry arches a framework of timber wliose to)) surface is tinored over on a curve cor- responding exactly to the curve of the arch is used on wbhh to set the wedge-shaped stones of the arch ring. See Centrino, and illustrations in article V.lii.niNO. BiiicK Masoxkv. With due allowance made for the dilTerence of the material and the dif- ference in the dimensions of the blocks used, brick masonry corresponds very closely to dressed dimension stone range ashlar masonry. The bond iscd is varied eonsideralily. but is usually either the Kuglish bond or the Flemish bond. In the English bond the courses are alternately head- er* and stretchers, and in the Flemish bond the hrirk in each course are altcrnatelv headers and stretcliers. ( For further description and illus- trations of brick masonry, see 1Jlildi.o.) The mortar used in brickwork may be either lime mortar or cement mortar, the former being most used in ordinary building work. Practice varies in the amount of pressure allowed upon brick masonry, bvit it should carry safely a load of 20 tons per square foot when laid in lime mortar. Brick uuisonry is cliieliy used in buihling con- struction and in lining tunnels and constructing sewers. Uom])ared with stone masonry, brick masonry is not so strong as ashlar masonry, but it costs less, while it is stronger than rubble masonry, but costs more; it resists fire better and is at least eoually as durable against ordi- nary weathering as best stone masonry. Concrete J1.so>ry. Concrete masonry may consist of molded blocks of concrete laid like ashlar or squared stone masonry or of moni)lithic masses of concrete deposited or constructed in situ. In the first class of work the plastic con- crete (see Concrete) is rammed into suitable molds and allowed to harden, and then the hard- ened blocks are laid in the structure just asi similar blocks of natural stone would be laid In the second class of work the plastic concrete is deposited directly in the position it is to oc cupy in the finished structure, molds being used to confine the nuiterial to particular forms and positions when necessary. Concrete masonry is extensively used for ncarlj' all the purposes for wliieh brick and stone are now employed. For a comprehensive treati.se on masonry work, cmi suit: Baker, Treatise on Masonry Construction (Xew York, 1900) ; ilerrill, Htones for liuilding and Decoration (New York, 1891). See Build- ing; Builuinu-Sto.ni;; Brick; Ceme.nt; Con- crete; MoRT.vK; QuAKKY; Stone Cuttino and Dressing; and Stone, Arth-ici.^l. MASONS, Free. . secret fraternal organiza- tion of worldwide celebrity, and one credited by enthusiastic writers with great antiquity. The Order, however, is now conceded to have been instituted about the early part of the eighteenth century — the pretensions put forth to a date coeval with the building of the Temple at .Jerusa- lem, with King Solomon as the first grand master, being considered by those who have thor oughly investigated the subject as not worthy nf credit. The attempt also made to establish a connection between the fraternity and many of the sci-ret culls and organizations, such as tin- Eleusinian mysteries, the Pythagoreans, the Rosi eruei:ins and others, in the early stages of its existence, has also failed, the utmost a<- eomplished in that direction being the deter- tion of a certain similarity between the symboU and ceremonies of these older institutions and the system of ritual and rule observed by the ^iasonic Order — cireumambulation. the u~c of aprons, the forty-seventh jiroblem of Km clid. etc. .Another consideration which tend^ to discredit any connection between these older associations and the Freemasons is the fact that the conception of Masonry implies a cosmopol- itan brotherhood, which would have been impo;;- sible of realization in the earlier ages of the worlil's history. The more rational and the gen- erally acceiited theory regarding the origin of the society of Freemasons is. that it is the successor of the buililing associations of the ^liddle .ges of whicti the ^trinmctzcn nr stonemasons of Ger- many were a representative. The term Free- J I