= 
time her bottom was examined and found free from oxidation, the 
outer scales and rust had disappeared, leaving the bottom perfectly 
smooth and clean. Now a wood vessel during that time would have 
required her copper to have been four times renewed, as often recalk- 
ed, paid and painted, besides frequent and small repairs in replacing 
defective wood, and at the expiration of that time either condemned 
or thoroughly repaired, and if we add the value of the time required 
to eflect such repairs, the economy of using iron steamers will be 
found enormous. 
5. Perfect safety from fire is another of the great advantages to be 
realized by adopting iron steamers. The returns of steam vessels lost 
in one way or another, demonstrate that a great proportion of these 
losses have arisen from fire. 1t naturally follows that the premiam 
of insurance would be much less for iron vessels than wood. The 
present custom is the use of wood beams and deck, but were it neces- 
sary for still further security, iron might be substituted with equal 
ease for both. 
6. The danger of the vessel’s sinking by springing a leak, if not en- 
tirely obviated, is very much lessened. The facility of dividing an 
iron vessel’s hold into departments by iron bulk-heads, which can be 
made as tight and as strong as a boiler, is very obvious; therefore if 
a leak takes place in any one division, that division may be filled as 
highas the outer surface of the water, and the vessel be still compara- 
tively secure. Moreover, a leak at sea on hoard an iron vessel, may 
be much more easily discovered than it could possibly be on board 
wood vessels, as it would not be hidden by a mass of timber. Another 
advantage would be perfect freedom from the smell of the engine~ 
possible to make the bulk-heads tight. 
%. The danger from lightning is very much diminished, as the 
whole body of the vessel is a conductor of electricity. Lander’s voy- 
age to Africa in an iron steamer corroborates this fact, and I find the 
opinions of the most scientific men concur on this subject. The cap- 
tain of a steam vessel, who commanded a steamer on the Mississippi 
more than twenty years, told me that he never knew a steamer to be 
struck with lightning when her engine was at work. 
8. In tropical climates there is a great advantage in iron steamers, 
as the internal temperature of the hold would be very much cooled 
