MECHANICS AND USEFUL ARTS. 41 



ness in the ratio of the strain ; and, on the other hand, the convex or top 

 side, which has to bear the pull, or tension due to the suspended weight, 

 is formed of long plates, connected together by the system of chain riv- 

 eting, which Mr. Fairbairn first applied in the great tubular bridges 

 of Wales. The sides of the crane are of uniform thickness throughout, 

 the joints being covered with T iron, and externally with strips four and 

 a half inches wide. This arrangement of materials constitutes the ele- 

 ments of strength in the crane. From the closest calculations made, 

 it appears it would require a weight of 63 tons to break the crane. 

 With 20 tons, the permanent set or deflection of the jib was 3. 33 in., 

 and after remaining suspended 16 hours, the further deflection was, 

 0.64 in. The advantages peculiar to this construction of crane are its 

 great security, and the facility with which bulky and heavy bodies can 

 be raised to the very top of the jib without the least risk of failure. 

 London Mining Journal. 



CHINESE METHOD OF REPAIRING BROKEN CAST-IRON VESSELS. 



IT is well known that the Chinese are accustomed to repair cracked 

 or broken cast-iron vessels by means of a solder of melted iron. An 

 explanation of this process, as performed by the Chinese tinkers, is fur- 

 nished by Mr. Balestier, U. S. Consul at Singapore, in the following 

 letter to Thomas Ewbank, Commissioner of Patents : 



" MACAO, Feb. 6, 1850. 



" Sir, According to your desire, T have carefully observed the Chinese 

 method of reuniting or joining together cracked or severed cast-iron 

 vessels, so as to make them useful as ever after an accident. Speci- 

 mens of utensils so mended have been forwarded to the Patent Office. 

 Among them is a cast-iron pan, measuring twelve inches in diameter 

 by four inches deep. A crack of three inches was made in it in the 

 first place, and, in the second, a piece was entirely broken off, giving 

 rise to two distinct operations. 



" The operator commenced by breaking the edges of the fractures 

 slightly with a hammer, so as to enlarge the fissures, after which the 

 fractured parts were placed and held in their natural positions by means 

 of wooden braces. The pan being ready, crucibles made of clay, were 

 laid in charcoal, and ignited in a small portable sheet-iron furnace, with 

 bellows working horizontally. As soon as the pieces of cast-iron, with 

 which the crucibles were charged, were fused, it was poured on a layer 

 of partly charred husk of rough rice, or paddy, which was previously 

 spread on a thickly doubled cloth, the object of which is to prevent the 

 sudden cooling and hardening of the liquid metal. Whilst in this liquid 

 state it was quickly conveyed with the right hand to the fractured part 

 under the vessel, and forced up with a jerk into the enlarged fissure, 

 whilst, with the left hand, a paper rubber was passed over the obtrud- 

 ing liquid, inside of the vessel, making a strong, substantial and neat 

 operation. You will thus remark that the art of the Chinese for re- 

 uniting cracked or severed cast-iron vessels, of all sizes, consists in 

 cementing them with cast-iron, whilst in the liquid state. 



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