292 Securities against Fire, fyc. 



As to the fall of the dome which covered a lofty building, lately 

 erected near London, and where it does not appear that there was 

 any fire ; if the dome was defective neither in its form nor in its archi- 

 tectural construction, it may be asked whether the iron contained in 

 its frame in the parts exposed to the sun, was not preternaturally 

 heated, compared with other parts not so exposed ; and whether this 

 did not cause a distortion in the whole of the fabric j or in other 

 words, did not cause a rupture in some parts, not to be resisted, which 

 was followed by the downfall of the dome. 



The preceding seven articles in this supplement have had reference 

 to circumstances connected with conflagrations. " 



and 15.) — 8. Datum. The first explosion instantly or within three minutes followed 

 this noise. The second explosion followed very closely, u lapping on to the first." 

 (15.) — 9. Datum. It is not said in what manner "the few square feet of iron plate 

 were connected with the copper parts of the engine ;" but it is plain, that the eban- 

 ges in the two metals were not exactly of corresponding natures. — 10. Datum, The 

 second explosion may have been aided by the sudden generation of steam, conse- 

 quent upon the water being thrown (during the commotion which things soon un- 

 derwent) upon heated copper, capable of generating an " uncontrollable quantity of 

 steam ;" which steam had to pass a tube of 20 feet in length and 10 inches in diam- 

 eter, before it reached the safety valve. — -11. Datum. The copper was bent in 

 parts in an extraordinary manner; that is, folded in massy doublings like a garment. 

 In other words, the copper maybe supposed to have contracted its dimensions: 

 that is, I think we may say that in the case of the copper of the boiler, it was not 

 merely ruptured ; especially as the body of water and of steam maybe supposed to 

 have given an even distention to the copper from within. (See report p. 5 and other 

 places.)— 12. Datum. We may conclude, that it will in future be wise to direct, 

 that all the connected parts of the steam engine containing water or steam, should be 

 made out of one metal : and that such other precautions should be taken as to steam 

 engines in steam boats, as foreign governments (English and French) have discover- 

 ed b^ experience to he preventive of mischief. — We add, that a strong suspicion is to 

 be entertained, that the safety valve was not sufficiently attended to, during the stop- 

 page of \he steam boat New England at Essex ; and it is clear, that the door of the 

 furnace w*s not closed, but was left open so as to admit the entry of air to increase 



the heat. Under these circumstances, the boiler, &c. had not a corresponding 



strength. 



To the above Data collected from the interesting Report on the cause of the ex- 

 plosion of the boiUr of the steam boat New England, we add the following particu- 

 lars from Mr. Dal ton, 1. Iron expands nearly one eight hundredth part in length 

 or 265 part in bulk by 180° of Fahrenheit. 2. Iron is to copper in expansion as 2 

 to 3. 3. Although Mr. D differs from Mr. Smeaton on these subjects, it m because 

 Mr. S. ha« omitted some points id his calculation, and not because he was incorrect. 

 4. We mention by the by, as something curious, that Mr. D. places the greatest 

 density of water a 36% Fahrenheit, and not at 40°. See new system of Chemical 

 Philosophy, Part I. pp. 28—33, and 43. N. B. It is unfortunate that the expan- 

 sions of metals have not been tried beyond the temperature of 180° of Fahrenheit 



