t British
36-gun frigates were the _Brilliant_ and _Pallas_, built in 1757. Their
main armament also consisted of 12-pounders. French frigates of the same
date were of larger dimensions, as is proved by the following table
which compares the principal measurements of the _Brilliant_ and of the
French frigate _Aurore_:--

----------+-----------+-----------+----------------------------------
Name of | Length of | Breadth. | Depth of | Tonnage. | Complement.
ship. | gun-deck. | | hold. | |
----------+-----------+-----------+----------+----------+------------
| ft. in. | ft. in. | ft. in. | |
| | | | |
Brilliant | 128 4 | 35 8 | 12 4 | 718 | 240
Aurore | 144 0 | 38 8-1/2 | 15 2 | 946 | 250
| | | | |
----------+-----------+-----------+----------+----------+------------

In the year 1761 a most important improvement was introduced, which
greatly increased the usefulness of ships. This was the discovery of the
value of copper plates as a material for sheathing their bottoms.
Previously to this period lead was the metal used for sheathing
purposes, and even it was only employed occasionally. In other cases the
bottoms of vessels were paid over with various compositions, the
majority of which fouled rapidly. The first vessel in the navy that was
copper-sheathed was the _Alarm_, a 32-gun frigate. At first the use of
copper caused serious oxidation of the iron bolts employed in the bottom
fastenings, and copper bolts were substituted for them.

About the year 1788 the dimensions of the various rates were again
increased in order to keep pace with the improved French and Spanish
ships. In the year 1780 the 38-gun frigate founded on a French model was
introduced into the navy, and continued to be much used throughout the
great wars at the close of the eighteenth and the commencement of the
nineteenth century. The first British frigate of this rating was the
_Minerva_, which measured 141 ft. in length of gun-deck; 38 ft. 10 in.
width of beam; 13 ft. 9 in. depth of hold, and 940 tons--figures which
were evidently based on those of the _Aurore_, captured in 1758 (see p.
128). In 1781 and 1782 two very large French frigates were captured.
Their names were the _Artois_ and _Aigle_, and they exceeded in size
anything in this clas