BUILDING. 



Joints ; so that they cannot descend in the 

 inclined direction of the stair, not yet in 

 a vertical direction ; the upper sully of 

 every step forms an interior obtuse an- 

 gle, called a back rebate, and the lower, 

 of course, an exterior one; and the joint 

 formed of these sallies is called a joggle. 

 The upper part of the joint may be level 

 from the face of the risers, to about one 

 inch within the joint. 



This is the plane of the tread of each 

 step, continued one inch within the sur- 

 face of each riser ; the lower part of the 

 joint is a narrow surface, perpendicular 

 to the rake of the stair, at the end next 

 to the newal. In stairs constructed of 

 most kinds of stone, the thickness of eve- 

 ry step, at the thinnest place of the end 

 next to the newal, has no occasion to ex- 

 ceed two inches, for steps of four feet in 

 length, that is, by measuring from the in- 

 terisr angle of every step perpendicular 

 to the rake. 



The thickness of steps at. the interior 

 angle should be proportioned to the 

 length of the step ; but allowing that the 

 thickness of the steps at each interior an- 

 gle is sufficient at two inches, then will 

 the thickness of the steps at the interior 

 angles be half the number of inches that 

 the length of the steps has in feet ; thus 

 a step five feet long would be two inches 

 and a half at that place. 



The stone platform of geometrical 

 stairs, viz. the landing half spaces, and 

 quarter spaces, are constructed of one, 

 two, or several stones, according to the 

 difficulty of procuring them. When the 

 platform consists of two or more stones, 

 the first platform stone is laid upon the 

 last step that is set, and the one end 

 wedged in the wall : the next platform 

 stone is joggled, or rebated, into the one 

 next set, and the end again fixed in the 

 wall, as that and the preceding steps are, 

 and every stone in succession, till the 

 platform is completed. If there is occa- 

 sion for another flight of steps, the last 

 platform becomes a spring stone for the 

 next step ; the joint is to be joggled, as 

 well as all the succeeding steps, in the 

 same manner as the first flight. Geome- 

 trical stairs, executed in stone, depend 

 on the following principle : that every 

 body must at least be supported by three 

 points, placed out of a straight line, and, 

 consequently, if two edges of a body in 

 different directions be secured to ano- 

 ther, the two bodies willbeimmoveable in 

 respect to each other. This last is the 

 case in a geometrical stair; one end of a 

 stair stone is always ta :( ed into the wall, 

 and one edge either rests on the ground 



itself, or on the edge of the preceding^ 

 stair stone, whether the stair stone be a 

 plat or step. The stones forming a plat- 

 form are generally of the same thickness 

 as those forming the steps. 



Roofs. Roof is that part of a building 

 raised upon the walls, and extending over 

 all the parts of the interior, which con- 

 sists not only of the covering or exterior 

 part, but of all the necessary supports of 

 that part, for protecting its contents from 

 inclement seasons. There are many 

 forms of roofs, the most simple of which 

 is that which has only one plane, and is 

 called a shed roof ; but the form which 

 has always been, and still continues to be, 

 in most general use, wherever the nature 

 of climate requires it to be raised, is that, 

 the vertical section of which consists of 

 two sloping sides, is consequently trian- 

 gular, and called a span or pediment 

 roof. 



Here it will be proper to say some- 

 thing of the changes of inclination or 

 pitch which have prevailed in this simple 

 form, among different nations, from time 

 to time, arising as well from the nature of 

 the climate 33 the caprice of the people, 

 and as transmitted down to the present 

 age. The ancient Egyptians, Babyloni- 

 ans, and Persians, as well as other eastern 

 nations, and also the present inhabitants 

 of those climates where rain seldom ap- 

 pears, make their roofs quite flat. The 

 ancient Greeks, perceiving t^ie inconve- 

 nience of this, raised them in the middle, 

 with a gentle inclination towards the 

 sides; the height from the middle to the 

 level of the walls not exceeding one- 

 ninth or one-eight part of the span ; as 

 may be seen by many ancient temples 

 still remaining in that country. The Ro- 

 mans made the height from one-fifth to 

 two-ninth parts of the span. After the 

 decline of the Roman empire, high pitch- 

 ed roofs began to be in general request 

 all over Europe, and the vertical section 

 of that which most generally prevailed 

 seems to have been an equilateral trian- 

 gle, which was considered as the standard. 

 In Germany, this has been remarkable 

 from very remote antiquity, as appears 

 from Vitruvius : the equilateral pitch, 

 and that of a higher one, appears to have 

 continued as long as pointed architecture 

 prevailed. 



When Grecian and Roman architecture 

 was first introduced into this country 

 from Italy, roofs began to be made lower, 

 and the rafters were three-fourths of the 

 breadth of the building: this was called 

 true pitch, and subsequently the square 

 seems to have been considered as the 



