Moreover, merchandise exported is usually valued by the customs at the moment of leaving the port of embarkation; that is, when it has so far paid only very small sums for carriage and transportation. Imported merchandise, on the other hand, is valued at the time of its disembarkation, in the ports of arrival or destination, when it is already burdened by all the expenses incident to a long voyage; such as freight, insurance, brokerage, etc. It very often follows that in calculating the results of a given transaction, and in supposing, moreover, that the estimates are perfectly correct, we often find a perceptible difference between the comparative figures of exportation and importation, which must be settled (so it is often supposed) by a payment of cash, whereas in reality the whole transaction consists of a simple exchange of commercial products.[115] [Footnote 115: See _Nouveau Dictionnaire d’Economie Politique_, Article _Balance du Commerce_, by Georges Michel.] Besides these general causes of error in the calculation of the principal elements of the Argentine balance-sheet, there are others affecting the Argentine which we might call local, which arise from the manner in which the customs estimate the merchandise imported. We have seen that the Customs Administration bases the collection of duties upon a valuation tariff, the exaggerations of which have given rise to the liveliest complaints. As for the statistics of the exports of national produce, they are based upon the market prices. As for the foreign capital invested in securities, etc., we know its value within a fair degree of approximation. But it is quite otherwise with the large masses of foreign capital employed or invested privately, whether in mortgages, commercial enterprises, urban or rural properties, or in a thousand other directions; we know neither the total amount nor the interest, nor profits which it produces. These profits are a permanent cause of uncertainty with respect to the establishment of the national balance-sheet. Apart from these causes already enumerated there is yet one other which deserves to be taken into account; it consists of the sums which Europeans who are established or have become enriched in the Argentine send each year to their families abroad. We have, unhappily, no means of estimating the importance of this sum. Finally, a cause of inaccuracy which is felt at present as it never has been before, has its rise in the ever-increasing number of natives of the Argentine who leave their country for Europe, their purses well lined, and themselves ready to spend their money in superfluities or luxuries, or in travelling from place to place. According to the information furnished us by the agents of various steamship companies, 10,805 first-class passengers left the Argentine for Europe in 1908, in search of more or less costly amusement.