376 Mr. Pattinson on the 



sal-ammoniac, as ordinarily employed by engine-wrights. The 

 steam is worked at a pressure of thirty-five pounds per inch. 



The joint between the top of one of the boilers and the 

 seat of its safety-valve had given way, and steam was issuing 

 forcibly through this aperture, when on Tuesday, September 

 29th last, the engine-man, William Patterson, while standing 

 with this current of steam blowing upon his legs, took hold of 

 the weight attached to the lever of the safety-valve, to try the 

 strength of the steam, when he felt a peculiar pricking sen- 

 sation in the ends of his fingers, but as the steam prevented 

 him from seeing distinctly, he thought he had merely struck 

 his fingers rather suddenly against the weight. On Friday, 

 October 2nd, on taking hold of the lever, he again felt a sen- 

 sation in his fingers of the same kind as before ; and on 

 Saturday, the 3rd, on touching the weight, this sensation was 

 stronger, and more distinct ; so much so, as to arrest his at- 

 tention and lead him to mention it to some other workmen 

 employed about the engine, who all handled the weight, and 

 convinced themselves that there was something about it very 

 unusual. During the time they were thus employed, Patterson 

 applied his finger gently to the lever, and perceived a spark. 

 This was repeated by the whole party, and they soon found 

 that sparks could be obtained from any part of the end of the 

 boiler, as far as the valve upon the steam-pipe connecting the 

 two boilers, and also from the pipe through which the sediment 

 is blown, as already described. They observed further, that 

 while standing in the volume of steam issuing from the joint, 

 and touching the boiler, these sparks were always much 

 stronger than when the boiler was touched by a person not 

 in the current of steam. In one or two cases, according 

 to their account, when the current of steam issuing from 

 the joint was very strong, the person exposed to it being 

 probably partially insulated by standing upon the dry and 

 warm brick-work surrounding the boiler, gave strong sparks 

 to others out of the current on bringing his hands to theirs ; 

 and once or twice they felt, under these circumstances, some- 

 thing like a slight electrical shock. It may be observed, that 

 at this time the weather was exceedingly fine and dry. It was 

 not long before the engineer of the colliery, Mr. Marshall, be- 

 came acquainted with these circumstances, and his first feeling 

 was to apprehend that the boiler was in danger of exploding, 

 for, as he said, "when there was fire on the outside of the boiler, 

 he did not know what there might be within." He accordingly 

 sent to Messrs. Hawks's, of Gateshead, who built the boiler, for 

 a person toexamine it, and Mr. Golightly, their manager in that 

 department, went out on Wednesday, the 7th inst., for that pur- 

 pose. He gave his opinion as to the safety of the boiler, and 



