CHIMNEY. 



CHINA. 



Ill 



thickness at ground level, 7 bricks ; thickness 

 at the top, 1 bricks. From this it will be seen 

 that the portion below ground, which contains 

 not only the foundation proper, but also the 

 flues, with their arches and coverings, occupies 

 a depth of 14 feet. The flues are four in num- 

 ber, placed at right angles to each other, so as 

 to form an equilateral cross in the plan ; they 

 are of rectangular section, about 7 feet wide, 

 and 9 feet high each, and arched both at the 

 top and bottom. The foundation below these 

 flues is built up from hard bricks, all placed on 

 edge throughout several superposed layers up 

 to the sides of the flues, which are arched and 

 lined with fire-bricks. The masonry above the 

 flues is built with the bricks laid flat in the 

 usual way. The internal diameter at the base 

 is 20 feet, and it gradually contracts toward 

 the top to 10 feet 4 inches diameter. Up to a 

 height of 50 feet there is an internal lining of 

 fire-brick placed within the chimney proper, 

 with an air-space between it and the outer wall. 

 The outline of the whole structure is of extreme 

 simplicity, viz., the form of a truncated cone, 

 without any deviation, ornamentation, or addi- 

 tion. The " batter " is straight from the bot- 

 tom to the top, and there is no " cap " or other 

 protruding ornament at the top. The section 

 is circular throughout. Professor Rankine, in 

 his report upon the stability of this chimney, 

 calculated the maximum pressure of wind 

 which this structure is capable to resist at dif- 

 ferent horizontal joints, and the figures given 

 by him are as follows : 



Height of joint above ground. 

 360 ft. 



280 ft. 

 200 ft. 

 120 ft. 

 40ft. 



Greatest safe pressure of wind. 



90 Ib. per sq. ft. 

 64 Ib. " 

 63 Ib. " 

 66 Ib. " 

 74 Ib. " 



From this it appears that with the straight out- 

 line the line of weakness, or the point of least 

 stability, is somewhere about 200 feet from the 

 ground, and that at this spot the chimney 

 should be thicker, in order to have an equal 

 stability throughout. Yet, as the capability of 

 resistance at any point is in excess of what it 

 will ever be called on to exert, simplicity of 

 construction is more important than the theo- 

 retical outline. 



The Port Dundas chimney has, during its 

 erection, undergone one of the most interesting 

 and curious operations known in masonry prac- 

 tice, viz., the straightening by sawing the mor- 

 tar-joints. The mortar in the newly-built por- 

 tion of the work being still soft and plastic, the 

 pressure of the wind caused a lateral deflection 

 of the column, amounting to 7 feet 9 inches 

 from the vertical at the top. The whole struc- 

 ture was thereby endangered, and, in order to 

 restore its stability, it was necessary to bring 

 it back to the vertical line. The operation of 

 sawing, which was then resorted to, consists 

 in attacking the mortar-joints at the windward 

 side, and to reduce their thickness, so as to 

 compensate for the compression of the mortar- 



joints at the opposite side, effected by the 

 pressure of wind. The sawing was done by 

 first removing a portion of the brickwork in- 

 side the chimney, forming a groove about 

 14 inches wide half round the interior surface 

 of the chimney. Narrow holes were then cut 

 out by means of chisels, the workmen standing 

 upon the internal scaffolding, and working ex- 

 clusively from the inside. A saw with a single 

 handle in reality an old carpenter's saw was 

 the instrument employed. It was passed througl i 

 one of the holes cut out so as to work through 

 a horizontal mortar -joint, and it was then 

 worked by hand, removing the mortar, as it 

 proceeded through the joint, through part of 

 the half circle on the windward side. Gener- 

 ally two saws were simultaneously employed, 

 working in opposite directions toward each 

 other. The mortar-joint operated upon was 

 kept wet by a jet of water during the whole 

 process, and the removed brickwork in the 

 interior was replaced by fresh bricks as the 

 sawing proceeded. As soon as the greater 

 portion of any one mortar-joint is sawn through, 

 the effect produced upon the superincumbent 

 mass causes the latter to settle, and a consid- 

 erable pressure is thereby exerted upon the 

 saw, making it difficult to withdraw. If the 

 precaution is taken to commence sawing at the 

 lowest joints, and proceed in succession to the 

 higher cuts, this difficulty is considerably less- 

 ened. In the case of the Port Dundas chim- 

 ney, sawing was commenced at the top, 128 

 feet below the chimney-cope, and twelve cuts 

 were made in unequal distances, varying from 

 12 feet to 49 feet. Judging by the effects pro- 

 duced by each incision, the spots were selected 

 for the next cut by proceeding gradually down- 

 ward until the last cut, 41 feet from the ground, 

 restored the whole chimney to a perfectly per- 

 pendicular position. The chimney after sawing 

 stood more correctly perpendicular than it had 

 been before the action of the storm, and it is 

 now more correct in that respect than the 

 majority of well-built chimneys of much smaller 

 sizes. The operation of sawing occupied 

 nine days, from September 21st till October 

 1st, 1859, and the chimney has from that date 

 remained in its perfect condition, requiring no 

 further strengthenings or repairs. 



CHINA, an empire in Eastern Asia. Em- 

 peror, Ki-Tsiang (before his accession to the 

 throne, Tsai-Sung), born April 5, 1855 ; suc- 

 ceeded his father, Hieng-Fund, August 22, 1861. 

 The estimates of the area of China Proper vary 

 from 1,294,000 to 1,548,000 English square 

 miles ; and of the area of the dependencies of 

 China, from 3,012,000 to 3,118,000 English 

 square miles. The total area of China and de- 

 pendencies is given byBehm (GeograpJi. Jcihr- 

 luch, vol. ii.) as 4,695,334 square miles. The 

 population of China Proper was in 1812 esti- 

 mated at 361,993,179; in 1842, at 414,686,994; 

 and in 1866, at 450,000,000. The population 

 of the dependencies of China is estimated as 

 follows: Mantchooria, 3,000,000; Mongolia, 



