1 28 Mr. J. Taylor on the Accidents 



to (y\ or 7 feet. The former are usually \ an inch thick, and 

 the outer case fths. 



The weakest parts of this construction have generally been 

 supposed to be, the outer tube, by having too great a diameter 

 for the strength of iron used, and the ends of the boiler, which, 

 by being square and riveted to angle iron, are more likely to 

 break than if a spherical form were adopted. It does not ap- 

 pear, however, in practice, that these have been the first parts 

 to give way. 



The advantages which this boiler seems to possess over 

 others may be shortly stated. It has been found, by comparing 

 the duty of the engines by means of the monthly reports, and 

 checking this by the observations of the agents, that the fuel 

 goes further in them than in any others yet tried. Circum- 

 stances, at first sight apparently trivial, may perhaps conduce 

 to this result. I suspect that the peculiarities of coal of different 

 districts influence more the success of different kinds of boilers 

 than has been generally supposed. In Cornwall all the coal is 

 from South Wales, and is brought from the neighbouT'hood of 

 Swansea ; it is less bituminous than most other coal, is not easy 

 to inflame, but gives a strong and durable fire : it is subject to 

 the objection of producing a great deal of clinker, and this 

 unites with and adheres strongly to any brick-work which the 

 fire may come in contact with, so as to require frequent cleans- 

 ing of the fireplace. In the boilers I have been describing 

 there is no brick-work near the fire, the clinker does not ad- 

 here to the iron sides, and the process of cleansing is easy 

 and rapid ; the action of the fire is therefore regular and un- 

 interrupted. 



The second kind of boiler used is a single tube made of 

 •wrought iron plates of considerable length but of small dia- 

 meter, 



