harbor; on the other hand, a naval force stationed within the inner harbor, and acting under the protection of forts at the Narrows, might also furnish a good, though perhaps less certain protection for this outer roadstead.  Here, then, we might well consider the question of relative cost and economy of support of the proposed fortifications, and of a home squadron large enough to effect the same object, and to be kept continually at home for that special purpose.  If we were to allow it to go to sea for the protection of our commerce, its character and efficiency as a harbor defence would be lost.  We can therefore regard it only as a local force—­fixed within the limits of the defence of this particular place—­and our estimates must be made accordingly.

The average durability of ships of war in the British navy, has been variously stated at seven and eight years in time of war, and from ten to twelve and fourteen years in time of peace.  Mr. Perring, in his “Brief Inquiry,” published in 1812, estimates the average durability at about eight years.  His calculations seem based upon authentic information.  A distinguished English writer has more recently arrived at the same result, from estimates based upon the returns of the Board of Admiralty during the period of the wars of the French Revolution.  The data in our own possession are less complete; the appropriations for building and repairing having been so expended as to render it impossible to draw any accurate line of distinction.  But, in the returns now before us, there are generally separate and distinct amounts of the timbers used for these two purposes; and consequently, so far as this (the main item of expense) is concerned, we may form pretty accurate comparisons.

According to Edge, (pp. 20, 21,) the average cost of timber, for hulls, masts, and yards, in building an English 74 gun ship, is L61,382.  Let us now compare this cost of timber for building, with that of the same item for repairs, for the following fifteen ships, between 1800 and 1820.  The list would have been still further enlarged, but the returns for other ships during some portion of the above period are imperfect: 

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       Name of Ship. |No. of| When | Repaired from | Cost.
                        |Guns. |built.| |
   ------------------------------------------
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   Vengeance,...........| 74 | -- | 1800 to 1807 | L84,720
   Ildefonso,...........| 74 | -- | 1807 to 1808 | 85,195
   Scipio,..............| 74 | -- | 1807 to 1809 | 60,785
   Tremendous,..........| 74 | -- | 1807 to 1810 | 135,397
   Elephant,............| 74 | -- | 1808 to 1811 | 67,007
   Spencer,.............| 74 | 1800 | 1809 to 1813 | 124,186
   Romulus,.............| 74 | -- | 1810 to 1812 | 73,141