PROCEEDINGS OF THE POLYTECHNIC ASSOCIATION. 771 



If we would prevent disasters we must carefully study cause and 

 effect — the rest to a practical mind is simple. 



A steam boiler, intended to work with a pressure of eighty 

 pounds to the square inch, is worse than a powder mill, if, under 

 any circumstances, that pressure can be increased one pound. 

 Some will say the safety-valve is a sufficient remedy, whilst others 

 contend that the same has been found wanting in many cases; 

 both parties are right. A steam generator, in the true sense of 

 the word, one that will make dry steam without super-heating in 

 any manner, one that will simply change the cohesive force of 

 the water into the repellant force of the steam, and leave the 

 water a dense mass, free from steam, wants only a simple and 

 reliable safety-valve. But a regular steam boiler — we had better 

 call it by its true name — a water boiler, wants more, or rather to 

 make it perfectly safe under all circumstances — well, it wants to 

 be kept cool. 



I have for years made heat and steam a speciality. I have 

 experimented during that time on a large and small scale, and 

 have carefully examined more than fifty 'exploded boilers, and 

 conversed with practical engineers and others, both in this and 

 the old country, on this subject, and I must own that the mor'e I 

 search and the more I can see into the laws that lie at the root 

 of the production of steam, the more I marvel — not that steam 

 boilers explode — but that they do not explode more often. On 

 a steamer I hold my life worth but little, when I think that there 

 is more dangerous power stored in the boilers, than there could 

 be in a hundred barrels of power, and, further, that this power is 

 in the hands of men knowing but little as to its nature. If an 

 engineer is asked how he is protecting human life he will point 

 to the glass guage, if such a thing is used at all, considering that 

 all is done that can be done when the water is at a sufficient 

 height. And yet there are many cases on record where it is 

 shown, beyond doubt, that, at the time of explosion, the water- 

 level was at its proper height. There are also many boilers, and 

 particularly of that class known as fire-box or locomotive boilers, 

 in which it is not an unknown occurrence to have water in the 

 upper and steam in the lower gauge. Are such boilers safe? 

 Are they constructed with any defined object, except to boil 

 water? 



All things in nature or art to be perfect must have faultless pro- 

 portions. The strongest column men can fashion is the most 



