ACCIDENTS AND KKl'AIKS IN TTNNKL8 277 



ease with which brick could be handled, it was decided to re- 

 build the walls out of brick instead of stone. 



In tearing out the old wall a hole was first cut through the 

 three bottom courses of the arch and gradually widened. When 

 the opening became four or five feet long, a small jack was 

 placed near the center of it and brought to a bearing against 

 the arch to sustain it After cutting the opening to a length 

 of from 7 to 10 ft depending on the stability of the earth 

 backing, the jack was removed and a piece of 8x16 in. timber 

 placed under the arch and brought up to a bearing with jacks. 

 One end of the timber rested on the old wall, the other on a seat 

 built into the adjoining section of new wall. Wedges were 

 then driven under the ends of timber and the jacks removed. 

 With this timber in place, the old wall could be taken dowu 

 with ease, the only trouble being that small stones and earth 

 fell in from above and behind the arch. Tliis was obviated 

 by placing a 2 in. plank across the opening and just back of 

 the 8x16 in. timber. At several points, however, the earth 

 backing was saturated with water, and it became necessary to 

 put in lagging as the old wall was removed. This timbering 

 would be taken out as the new work was built up. 



A suitable foundation for the new wall was secured at a 

 depth from 2 to 4 ft, and a concrete footing was used. The 

 section of the new wall was then built up as near as possible to 

 the 8x16 in. timtar; the timljer was then removed and the 

 new wall built up and keyed under the arch. 



The new wall had a minimum width of 'J.l ft at the top, 

 and 4 ft. at the base of rail, and was provided with weep holes 

 at intervals. T<> facilitate matters, work was carried on simul- 

 taneously at two or three different places, the intention la-ing 

 to get one place torn out and ready for the bricklayers by the 

 time they completed a section of the new wall at another 

 place. 



In rebuilding the arch, sections extending from the spring- 

 ing line up as far as was necessary to obtain the desired clear- 



