We have made little mention, in the foregoing pages, of the actual tonnage or dimensions of ships, for the reason that the figures would be for the most part unreliable or misleading in import. The basis on which tonnage was measured was constantly changing. It was difficult to obtain accurate measurements of the principal dimensions; length, especially, was an indeterminate dimension, and, in the days when a large fore and aft rake was given, the length of keel gave no indication of the over-all length. Even if the over-all dimensions could be accurately measured, they gave small information as to the form of the hull: the fullness or fineness of the lines, the form of the bow-curves and tuck, the position of the section of maximum breadth, both longitudinally and relatively to the water-line--proportions on which the sailing qualities of a ship largely depended. In the seventeenth century the tonnage figures were generally untrustworthy; the _Sovereign_ was quoted by three different authorities as being of 1141, 1637, and 1556 tons burthen. In the eighteenth century tonnage and dimensions possessed greater comparative value. We confine ourselves to quoting the following table of typical dimensions, taken from Charnock, showing the gradual expansion which took place in the hundred years which have just been reviewed. ---------------------+----------+-------+-------+------+------- Establishment | Length | Keel |Breadth| Depth|Tonnage |(gun-deck)| | | | ---------------------+----------+-------+-------+------+------- 1706 } | 171′ 9″ |139′ 7″| 49′ 3″|19′ 6″| 1809 1719 } 100-gun ships | 175′ 0″ |140′ 7″| 50′ 3″|20′ 1″| 1883 1745 } | 178′ 0″ |145′ 2″| 52′ 0″|21′ 6″| 2091 _Commerce de | | | | | Marseille_ (120) | 208′ 4″ |172′ 0″| 54′ 9″|25′ ½″| 2747 _Caledonia_ (120) | 205′ 0″ |170′ 9″| 53′ 8″|23′ 2″| 2616 ---------------------+----------+-------+-------+------+------- §