On Friday, the 2d inst., a boiler of the Mississippi steamer H.R.W. Hill exploded, instantly killing thirty-nine persons. The same day a boiler blew up at New-Haven, fatally injuring three or four persons. The next day the boiler of the tow-boat Baltic exploded in Mobile Bay, killing and fatally injuring several people. On the 24th ult. -- a little over a week ago, a boiler explosion occurred at Lee, and another at Lowell; and the day before there was another at New-Orleans, each one killing its man and injuring others.
Meanwhile boilers are multiplying wherever power is required -- under saloons, warehouses and sidewalks; and without many exceptions, the principle upon which their proportions and quality are dictated, is -- how to save first cost.
The causes of boiler explosions have been so thoroughly investigated within a few years, that the only safe and reasonable ground to take about them is that they are never accidental -- that they can always be prevented -- that they are, in fact, nothing more nor less than bad material, malconstruction, or reckless management. That either electricity or hydrogen gas (the only gas that can be set free in a boiler,) can be a cause of explosions, is quite impossible. On this subject, the leading chemists of Europe have given an unanimous opinion, sustained by the most conclusive experiments. Not only is there too little electricity generated, but the metal of the boiler and its attachments conduct what there is to the earth. And there can be too little hydrogen gas made in a boiler to cause an explosion, while what is made will not explode without there is oxygen from without admitted to it, after which the steam would prevent ignition, even if there were heat enough present to ignite the explosive compound. Without detailing the facts and principles involved, since nothing short of a complete essay on the subject would enable the unprofessional reader to convince himself, it is sufficient for present purposes to mention that the very best professional opinion, or rather, belief, is, that all explosions begin with the simple, and in itself harmless rupture due to overpressure, or of the inability of the boiler to carry the ordinary pressure. While a part of a boiler may be five times stronger than the ordinary force tending to rupture it, (this is the common proportion of actual to working strength,) another part, one plate or one strip of plate, or a single joint or a single rivet, may be so defective as to be on the point of rupturing, from the first, and may at last yield at a minimum pressure, carrying total destruction with it. There is a difference in the quality of the best boiler plates which is fearful enough to contemplate; but when we consider that cheap plates are made, which, instead of carrying 60,000 pounds to the square inch, will break into pieces under a heavy blow from a hand-hammer, and that there are thousands of steam-engine owners who are willing to risk everything to save first cost, who invariably get the cheapest work; and, moreover, that too many boiler-makers are capable of using anything which the outside public will recognize as iron, we shall observe where we stand as to the original quality of the boilers which strain and simmer above, around, and beneath us in our daily walk.
But the gradual deterioration of boilers is probably the leading cause of their failure. And to this and its detection and remedy we would direct especial attention. Among the 1,618 boilers under inspection by the Manchester Boiler Association in 1859, 14 boilers were found to be in a dangerous condition and 100 in an unsatisfactory condition from the fracture of plates, while there were 44 cases of dangerous and 153 cases of unsatisfactory corrosion, besides other defects. One explosion only occurred, instead of perhaps 20 which must have taken place, without this rigid system of examination. During the month of October alone, the examining engineers of this Association made 765 visits, and discovered among the serious defects which were at once remedied, 12 cases of corrosion, 15 of fracture, 38 safety valves out of order, 13 pressure gauges, inaccurate, 18 water-guages, defective, 10 blow-off cocks, dangerous, and 22 furnaces out of shape; there were 50 boilers without glass water-guages, 31 without blow-off cocks, 65 without back-pressure valves, 12 without pressure-guages, and 4 with fusible plugs corroded. These are boilers which are under constant inspection. Just think of it; we should like to know the state of several hundred boilers in this City that are not inspected, and of the scores of them that have never been looked at by an engineer since they came into service -- boilers which were not only bought at the lowest figure, but which are at the exclusive mercy of raw laborers who never attempt to discover defects, and who could not recognize them when pointed out and explained. The breakage of iron fixtures and structures is a most common circumstance, and because this first simple fracture is usually the end of the matter, we think very lightly of the multitude of causes which are constantly at work, destroying the texture of the metals. But after the rupture of boiler plate, there usually follows an explosion, and we are all aghast at the terrific results, as if there was anything unprecedented or unexpected about them. While it is always more economical, in the long run, to prevent disaster by rigid examination and immediate repairs, no very fearful results generally occur from letting defect show itself in failure, as in case of vehicles, implements, and any machinery, except that of railways and vessels. But we cannot afford to risk the rupture of boiler plate -- of iron which in almost any other service might fail harmlessly enough. The most rigid scrutiny will sometimes overlook fatal defects -- instead of which nine-tenths of all our boilers are never examined at all.
People may undertake to sneer at the theories and deductions of scientific men, and to insist on the impenetrable mystery of boiler explosions. One thing, however, they must admit that the metal of boilers is exposed to unusual causes of deterioration, and that a thin and weak vessel will not resist a certain pressure so safely as that of known uniformity and strength. Simple as this is, it is enough. If the owners of boilers will only practice what they believe, these terrible slaughters will rarely occur. Till they do practice -- till they at least make some show of caution by subjecting their boilers to frequent and competent inspection, the public should; and we hope it will, brand them as wilfully accessory to the murder of any victims whom their boilers, exploding, may kill. And that there are hundreds of boilers certain to blow up, no intelligent person who is at all familiar with the subject, will dare to deny.
On the whole, we advise the traveler, as he sets out on the journeys of the coming Winter, in view of the rotten boilers and bridges, the cinder plates and tinder appointments of ships without bulkheads, and the destruction of trains by the alternate rigidity of frost and violence of freshet, to assure his life and make his peace with Heaven.