The Construction of Large Tunnel Shafts, Volume 103

angle of intrados Apply the template arc A formula axis H'C brickwork centre line CHAPTER chisel draft circular opening cloth convex mould struck cosec Covent Garden cross section Crown 8vo curve of development curve of sines curved mould cylinder D. K. CLARK dimensions distance drafts be sunk draw dressed Engineer equal face flexible straight-edge flexible zinc plate Folding Plates front inner edge intrados and extrados joint keystone laggings length Let the angle line drawn lower side bed LUDGATE HILL oblique arch obtuse templates parallel and twisting PETER BARLOW point B Figs points of intersection practical r.cos R+ e radiating line radius unity representing the arc right angles ring shown in Fig sloping bed spiral springing level springing line stock A B struck with radius subtangent superfluous stone tangent top bed TREATISE twisting rules upper side bed vertical lines voussoir forming Wood Engravings Woodcuts