1836.] St. Peters Church in Fort William. 213 



Vaulted roofs of side arches and pillars. — The vaulted roofs of the side 

 aisles were found in a most dilapidated state, as likewise the main 

 pillars at the points d'appui of the springing of the ribs, upon which 

 rested the load of the side vaults. Upon the removal of the punkah 

 beams (r*) shewn in the accompanying section, (which had never been 

 removed by any Committee) it was at once evident that the principles 

 upon which the equilibrium and consequent stability of the side vaults 

 and pillars depended, (and according to which they had originally been 

 constructed,) were entirely destroyed ; viz. 1st, the thickness of butment 

 inwards, originally given to the main pillars, had been reduced in the 

 direct line of thrust from 4 to 2 feet, by the perforation of large holes, 

 for the insertion of beams upon which to suspend punkahs ; 2nd, the 

 adhesive continuity of the cemented materials (upon which the stability 

 of pillars composed of brick and mortar so entirely depend) had been 

 completely disturbed in the vicinity of the holes, from the blows of tbe 

 iron instruments by which they had been made ; 3rd, the springing of 

 the main ribs, upon which the side vaults rested, had been wholly cut 

 away on either side as exhibited at (ss), by which the vaults, deprived of 

 their supporting points, sunk down both in haunch and vertex from their 

 original position, thereby greatly increasing the force with which they 

 pressed against the main pillarsf ; 4th, the main pillars being so greatly 

 weakened by the perforation of the holes, and the disturbance of the 

 cemented material, yielded inwardly^: to the extent of 4| inches from 

 the perpendicular, and became cracked entirely across ; the parts 

 marked (tt) splitting off from some of them. Thus all equilibrium was 

 inevitably destroyed. 



Vault of the nave, fli/ing buttresses, cleristory walls, 8fC. — The above facts 

 being established, the examination was carefully extended to the vault 

 of the nave, the flying buttresses, the external and cleristory walls 

 and towers : but with the exception of some cracks in the flying 



Ton. Cwt. 



* Weighing in each aisle, 1 3 



Ditto Nave, 2 6 



independently of the weight of the punkahs. 



f The exact estimation of their increased force is a question of much diffi- 

 culty, from its being connected with circumstances not within the reach of 

 calculation, viz. the amount of injury accruing to the arch and pillar by the 

 penetration of the rain into the spandrils and through the arch ; also the amount 

 of pressure from the sinking of the abutment of the cleristory walls, which rest- 

 ed in part on the arch : but that it must have been very great will be evident to 

 every one acquainted with the rules and principles of construction. 



X A slight deflexion of the pillars inwardly had been observed before the 

 punkah beams were inserted. This deflexion, Sir Christopher Wren states, is to 

 be observed in all the Gothic Cathedrals in Europe, from which it would appear 

 to be a circumstance incidental to this style of Architecture ; but that it is not 

 productive of any important derangement of equilibrium, is fully proved by the 

 great durability of the Gothic structures in Europe. 



