12 APPENDIX. 



The bottom and lower parts of the shell of the boiler should be treated with as much care 

 in construction, as it has been suggested to pay to the bottom of the flues ; and the chimneys 

 should invariably be made of iron, to step on a cast-iron ring fitted to the top of the boilers. 

 The cast-iron ring does not seem to be affected by the copper ; its situation accounts for it. 



23. COPPER FUNNELS have beenacomplete failure, in every instance of their adoption ; 

 they are rapidly corroded within the air casing, so as in one or two instances to have been 

 crushed by the effects of a gale of wind. IRON FUNNELS decay principally in the parts on 

 which the waste steam operates, and these plates require renewal more frequently than the 

 rest ; therefore it is better to carry the waste-pipe level with the top of the funnel : coal tar, or 

 red lead, or a mixture of both, is the best varnish I have known to be adopted for funnels, 

 which with care may last five or six years. 



In conclusion, I confidently express my opinion that COPPER BOILERS are very far 

 superior to Iron for marine purposes ; and that if the necessary precautions in construction be 

 observed, they will run for a considerable time without giving trouble of any kind. Tinning 

 the bottom plates, lately observed by Messrs. Maudslay and Field, I should certainly 

 recommend ; it will remove the chance of decay to a certain extent. Large pieces of iron 

 have frequently been sent into the flues by me, which have been completely decayed in a 

 short time; no doubt with some good effect to the copper, but without the possibility of being 

 estimated. If the cause be removed by attention to the suggestions on construction, a patch 

 will seldom be required ; consequently delays will be seldom experienced on account of the 

 boilers. The original cost is nearly as three to one on the iron ; this ought not to deter 

 companies, or the proprietors of foreign steam vessels, where the means of repair is not at 

 hand : besides, when unfit for further use, they will always make a good return as old 

 copper; an old iron boiler being, in general, worth little more than the cutting up. Copper, 

 again, is a better conductor of heat than iron ; and if the advantages of incasing marine 

 boilers with non-conducting matter were properly considered and availed of, boilers might be 

 reduced in capacity, weight, and expense, to the obvious account of the proprietor, and to the 

 increased stowage of fuel. More might be said, but the above, coupled with the fact that 

 the shell will scarcely ever be injured or decayed, will be sufficiently demonstrative ; when 

 iron boilers frequently require extensive repairs of the shell or casing, either from water 

 passing by the funnel on the top of the boiler, or from the unavoidable leaks of the deck and 

 comings around the steam-chest ; also the shell is decayed, from the salt, 8cc. on the line of 

 stoke-hole plates or flooring, as well as in the neighbourhood of most of the stay-bolts on 

 the back and sides, the bottoms being often totally decayed ; and these are parts which, 

 from their situation, cannot be attended to conveniently. The above facts are notorious in 

 iron boilers, when in many instances no other defect has existed ; indeed, copper boilers 

 appear to be almost invulnerable in those situations where in iron boilers, whether employed 

 or not, the work of decay is constantly going on. Many cases of delay and incapacity 

 could be mentioned from these causes alone, when important public service was most 

 urgent, not to mention that of individuals. 



It is a common practice in many vessels to throw water into the ash-holes, to cool the 

 cinders prior to sending them up ; the salt, which adheres to the ash-pit in consequence, has 

 sometimes destroyed the bottom plates, when every other part of the boiler was sound. I 

 have seen some instances recently, where the water discharged from the gauge cocks is 



