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strains, may be considered an important security against wear andtear. The durability of a substantial iron ship, always water-borne,will, I think, depend (accidents alone excepted) on the question ofcorrosion; and this again, in a great measure, on the care that istaken in cleaning and painting, which, when duly exercised, will befound to be of much advantage. But we have another great sourceof encouragement as regards the durability of iron vessels. We arenow reasoning from cases where little or no attention has been de-voted in the application of anti-corrosive substances—cases in whichnot only extremely thin plates have been used, but in which thegreatest neglect has frequently been evinced. Have we not everyreason to expect great and beneficial results in the preservation ofthe material, from the labours of the chemist, and the aid of theo-retical investigation ? Amongst the gentlemen engaged in this pursuit,Mr. Mallett, Civil Engineer, of Dublin, is worthy of the highest com-mendation ; and it may be confidently anticipated that we shall,ere long, be put in possession of the means of rendering ironvessels much more durable than they are at present. Mr. Mallett,in describing the results of his experiments on the corrosion of ironin salt water, made at the instance of the British Association, andin allusion to his patent anti-corrosion process, supposes it quite pos-sible in the progress of the art, to render iron as much proof againstoxidation as “ gold or platinum.” Under the disadvantages, how-ever, of the comparatively novel application of the material in lieuof wood, the loss from corrosion is by no means of an amountcalculated to cause the merchant or shipowner to hesitate "whichof the two to choose.”

We now turn to the consideration of the durability of timber-built ships. And where, I would ask, in the catalogue of objections,real or fancied, to iron ships, is there one to be found equal to thatdreadful scourge to wooden vessels—the dry rot ; the effects of whichare too well understood by shipowners to require any lengthenedremarks from me ? 1 should not, however, do justice to my subject

did I pass it over in silence. No age has been without its nostrums,its quackeries, and its “infallible remedies” for the dry rot, and noperiod has been so productive of them as that in which we live;but, from all I can perceive, this plague is as prevalent as ever. Acircumstance which has recently fallen within my observation isstrongly illustrative of this subject, as involving the comparative