166 JOURNAL OF THE PLYMOUTH INSTITUTION. 
tonnage returns for our port would have been very different. It 
may be taken as a general rule for small vessels that the register 
tonnage — which I ought to say is a roomage ton, being 40 cubic 
feet of space, represents about half their carrying capacity. 
In Devon and Cornwall the export and import trade depend 
very much upon one another, indeed more so than in most 
localities. Every export trade ought to be encouraged as much as 
possible, because the advantage is reaped in the imports directly ; 
and these being of general consumption, the advantage is obvious. 
We have the important clay harbours of Par, Charlestown, Fowey, 
and Pentewan. These are mainly supported by the clay industry. 
Last year Par shipped about 80,000 tons of clay, and imported 
about 20,000 tons of coals ; the imports being one quarter of the 
exports. Again, at Charlestown about 90,000 tons of clay were 
shipped, and 20,000 tons of coals imported. Obviously the 
exportation of these 170,000 tons of clay cheapened immensely 
the importation of the 40,000 tons of coals used in the locality. 
Similarly it is possible to send macadam from Penzance to all the 
Welsh ports, and to London and the North of England, at a 
workable price. The amount of import and export traffic 
which is done at Penzance, as compared with Falmouth, 
depends upon the area of the country, and on the railway 
rates. But the traffic at Plymouth depends very much more 
on the railway rates than either that of Falmouth or Penzance. 
Bristol is the great West-country port competing with Plymouth for 
commercial work through the railway systems ; for every change 
in the rate of, say, grain means a corresponding change in the area 
supplied fiom the one or the other port. Thus so long as grain 
can be imported to Bristol and carried from thence to Exeter 
slightly cheaper than it can be imported at Plymouth and carried 
to Exeter, a shorter distance by the way, so long will Exeter be 
supplied from the Bristol market. The importance of these 
railway rates, without going into details, is thus obvious, and their 
great influence upon harbour traffic. A slight increase in favour 
of one place for another means the diversion of a large amount of 
traffic from one port to another. 
I will now proceed to deal with another branch of our subject, 
one which claims our attention, if for no other reason, than that it 
