CAR
105
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of
a c ' lrve through points, by bending a lath, or slip of wood;
Covp y, i T“o" "J «
«-^ a cketing, and the construction of ribs in groined
jj .'I 1 " 8 ’ disposed in vertical planes, were first shown by, ‘‘Penny. In the latter, however, he divides the bases into
v en' ^ >arts ’ ‘ n order to place the ordinates, which is incon-l a ent > for the equi-distance of the ordinates leaves a veryare P orl "' (m °f the curves at each extremity, where theyt0 * ,e tu'ncerl only by the eye. This writer also“Pon eaCr j hed t' le formation of spherical and spheroidal niches,and Sei P*" c 'reular and semi-elliptic plans, with semi-circulare//>\J? IQl " ed ‘Pt' c faces, under the names of semi-circular andl P flc niches.
? r ‘ ce we owe the mode of framing roofs in ledgement,it a the beams and rafters laid out on a plane ; thoughp rev . Ust he remembered that the general outline had beenof '°“ s ly described by Godfrey Richards. The Squaringli»] lt 6 P ur lin of a circular dome, and of a conic roof or sky-tibs •’ t ' >e hacking of angle-brackets (and consequently ofn ai .,, m S e neral) by shifting the mould of the rib; the ordi-tl‘e (]. C ° nS t ruc ti° u °f groin-centering, and moulds for drawingof do a S° na l lines at the feet of the jack-ribs ; the coveringand tl 6S ’ ^ bending the boards from the base to the vertex ;al So ft* 6 stret ching out of the surfaces of coved ceilings, wereTo ^ descr ibed by this writer.e*t en • e 'writings of Batty Langley we are indebted for ther aft ei . ° n °f ^'e superficies of polygonal roofs with curvilinearc°n e p ’ and likewise the covering of the frustum of a semi-at r j f , r a soffit in a straight wall, with the axis of the coneTh e U a !’2' es to the plane of the wall.j°int s P , in p*ple of forming boards to cover a dome, with thec °tte . lln “ ,n g in horizontal planes, or on the surface' of aTlvu f a vei t ‘ c al axis, was laid down by Swan.
Plane' f° ex tending the superficies of a semi-cylinder on ahip. ax; s ° r t *’ e s °tht of an aperture in a circular wall, with°f the cylinder at right angles to the surface of suchas cover t j le sur f ace 0 f d ie cylinder contained
« 'Veen tl ” '' u,cl
first 6 yi ., le two walls and each spring of the aperture, wasnbl ted by Pain ; as was likewise the principle ofI'hg ° Purlins for an elliptic dome, though very imperfectly."'ritc-j, 811111 tot al of the geometrical constructions by these^ l a 'vin» lna ' V * >e com prised as follows: the use of the trammel;i'nftp,.^' lrve , d lines through points; ascertaining the lengths
as to
of
‘inter* ,...'-“o" ...v.
Oiirviiijj / an< the backing of hips for both straight andfec tan<>n] ar raPtei ' s ; framing of roofs in ledgement, whether°r elfinp ar or hevel on the plan ; squaring purlins for circularf ()J , lc d °tnes and cones ; the construction of curvilinearCe nt fcl .i n an Sh j .-br ac ket,s, polygonal roofs, and plaster groins ;N 1 , wifh gr ? ins 5 formin S a conic soffit in a straight
° r aiino- a * ax l s °f the cone at right angles to its surface;
; ar(( j C yh n< h'ic soffit in a circular wall, with an horizontal“°ard Sj the covering of polygonal roofs or domes with■ 'h'hesp • ° Se -i oints fall either in horizontal or vertical planes.I" the ' nve ntions, however, are far from being laid downre fi v >enti v St .happy manner. The text of these authors is^‘{flection . eure > and their diagrams, which have little0 ‘flforrn • "i' 1 '' are badly projected, and little calculatedt r arig eni • hey have likewise so far neglected the requisite|>is eilon ’ that their subjects are thrown together in atheir p,.- 8 J ura ble, without either attention to the affinityth ft 0f thr; n ^f> or their order of succession in. practice.
1 title of ' Cr;d works quoted, Price’s alone can justly claim“Ha Sley ig n eatise on carpentry.
^ 'flat h as general tolerably intelligent; he has treated on
„-- «1CJ awj luicmgcui ; uc lias uc" 011 u “
"taiiy ti.- as been done by his predecessors, and has attempted
ln g s of his own ; but liis labours have not been suc-Xii
hints ; but his errors are numerous, and his inventions few.Ilis text, also, is more unintelligible than that of any writerwho preceded him in this art.
The inventions and discoveries of the writers quoted, maybe reduced to the following : Sections of prisms at rightangles to one side or plane of the prism ; coverings ofprismatic and conic surfaces, in the most simple cases; andthe method of ascertaining the lengths and backings of hipa,To these principles, the Author of the ArchitecturalDictionary has added those of the intersection of one planewith another, the latter resting on three lines perpendicularto the former ; the geometrical construction of all cases inspherical trigonometry, by solid angles; sections of a prism,cone, or cuneoid, through any three given points; the sectionof a prism making a given angle with a given parallelo-grammatic section of such prism, and passing through anygiven line on the said section ; the section of a cone passingthrough any line on a given axal or vertical section, andmaking a given angle with that section ; the section throughany three given points on the surface of a body, of suchproperty that all sections parallel to a certain plane will besimilar figures, having the seats and heights of the pointsupon one of the similar planes, and another section of thebody in a given position to that plan, cutting all the saidsimilar sections ; the sections of various other bodies, whoseproperties are defined ; the formation of the edge of a thinpliable surface, which, when bent upon the surface of a prism,may coincide in its edge with a section passing through anythree given points on the surface of the said prism; theformation of the edge of a surface, to fit a conic section,passing through any three given points on the surface of thecone, while such surface and that of the cone coincide ; theformation of the edge of a thin pliable surface to fit the sec-tion of a body cut by any prismatic surface, while the pliablesurface coincides with that of the section made by the pris-matic surface ; the properties of the body being such, thatall sections parallel to a certain plane will be similar figures,given a section of the body parallel to one of these sections,and another cutting all the said similar sections in a. givenposition, and the intersections of the given planes on eachother.
These subjects include the finding of the sections of cylin-ders and cones, spheres and spheroids, and the coverings ofthese bodies, under the circumstances already stated. To these,the author has added the following inventions or discoveries,viz., the method of extending the surface of a cylinder orcylindroid, being the centre of an arched aperture in anoblique wall, terminated by the faces of the said wall; andthe covering of the surface of a part of a semi-cone, beingthe centre of an aperture, with its axis oblique to the surfaceof the wall which terminates such covering. In ascendinggroins, he has likewise shown the centering for brickwork,and ribbing for plastering; the construction of polygonal andannular groins, both level and ascending in a spiral, whetherfor centering or ribbing; cylindro-cylindric arches, or whatare commonly, but improperly, denominated Welsh arches;spherical niches, both for straight and circular walls, underany circumstances: the true methods of constructing penden-tive or spandral ceilings, either spherical or spheroidal; thebevels of purlins in all positions to the common rafters; theformation of boards for covering spherical domes, withoutlaying down either plan or section of the dome, entirelywithin the boards themselves; the forming of the lowerboards, without centres, in the covering of a dome, with thejoints in horizontal planes ; the formation of boards to covera spheroidal dome, with the joints of the boards in verticalplanes; the covering of an elliptic dome with one mould