20 
INTRODUCTION 
British ports, but may not be British in any other respect. It would, 
for example, include trade in Australian wool bought in Sydney on 
account of a Hamburg merchant, sent to London in a French sailer, 
and thence despatched to Hamburg in a German vessel. 
46. Statistics of external commerce usually include statements as to 
the description of the goods exported or imported, the quantities, the 
countries of origin or destination of the goods, and the value. In the 
case of many articles, and especially those most largely imported and 
exported, such as food-stuffs and raw materials, the description of the 
article presents no difficulty, so that one may deal with returns as to 
such commodities in making comparisons between period and period in 
the trade of the same country, or between different countries for the 
same or different periods without fear of being misled. But in many 
cases it is otherwise, and difficulties in making comparisons for the 
same country for long periods are constantly being made by tariff 
changes necessitating different classifications, and even where there are 
no tariff changes alterations in the classification of goods are often made 
simply with the view of giving a more satisfactory statement of the 
facts of commerce. However useful such changes may be from one 
point of view, it has always to be remembered that they have the draw- 
back referred to. This drawback arises, it should be added, even when 
increased care is used, and hence increased accuracy arrived at in the 
collection of the original data. 
47. Notes are also given on the individual tables as to the various 
practices in stating the countries of origin and destination. In some 
cases the practice with regard to values has been, and in one case still 
is, even more misleading than any of the practices that have prevailed 
with respect to the point just mentioned. In England the earliest 
attempts at the systematic collection of commercial statistics appear to 
have been made in 1697. From that time down to 1797 inclusive the 
values entered for English commerce and, after the union of the Parlia- 
ments in 1707, for that of Great Britain, were official values based on 
the prices of 1694 and for new articles on the price of the first year of 
their introduction. The so-called values were, accordingly, not true 
values, but for each commodity served to give indications of changes 
in quantity from year to year, while the totals had little meaning at 
all. - From 1798 in the case of exports declared values were added, not 
substituted, so that we have the absurdity in Porter’s Progress of the 
Nation 1 of two tables giving professedly the same thing, the value to 
the last pound of exports from the United Kingdom from 1801 to 1849, 
yet utterly divergent from one another, showing from 1820 onwards 
a steadily growing excess of official over declared values till in 1849 we 
have 
Official Value 
Declared Value 
> 
- Edition 1851, p. 356. 
wl 
. £164,539,504 
.  63.596,0256