By far the greater number had their money advised at a cost of five to fifteen per cent, usually ten per cent, as against the three-quarters per cent which would probably represent a maximum of loss by exchange to-day to tourists. An unknown quantity lay in the differences of values, which might yield a profit, or might involve heavy loss. Bimetallism prevailed all over Europe, and the values of gold and silver both relative to each other and positive, fluctuated far more violently than is the case to-day. When Cavendish returned to England after his first circumnavigation of the world, the plunder depreciated gold in London by one twelfth; in 1603 the exchange from Venice to London was twenty-eight per cent in favour of Venice; in 1606 it was six per cent higher London to Venice than Venice to London. But with all its disadvantages, remitting by advice was the most generally satisfactory and used method. The tenour of an average bill, however, has changed somewhat, "at sight" being the only one of the variable terms equally customary both then and now. Bills not drawn "at sight" were drawn at "usance," "half usance," or "double usance"; "usance" signifying a month as a rule. Exceptions were, of course, for longer distances, such as London and Venice, when "usance" meant three months; and how completely "usance" is a term of the past is shown by the fact that the periods implied by "usance," in the rare cases in which it is still found in use, have not altered since the sixteenth century, in spite of the advance in the quickness of communications. "Thirds of exchange," now nearly as extinct as "usances," were then kept in regular use by the uncertainty of the posts; and in view of the difficulties in the way of identification and the advantage that money-changers were likely to take of them, advices often contained a description of the payee.[139] Method No. 3, letters of credit, was a more expensive one than remittance by advice, but for places for which no "usance" was established, was obligatory; under favourable circumstances it might cost no more than ten per cent. There is evidence enough to justify conjecture that the English government allowed their credit to be used sometimes for the convenience of tourists in order to facilitate a watch being kept on their movements.[140] Barter also ought not to be wholly left out of sight. In Norway dried fish was more serviceable than coin, as was tobacco among Turks, the only people prompt to copy the English in the use of it for pleasure; but by the middle of the seventeenth century the same might be said of Western Russia. And there is the case of one Thomas Douglas in 1600 who could not make arrangements for four hundred crowns to be advised for him at Algiers, applying to the English government for leave to take with him duty-free the broadcloth he had bought with the money and meant to realise there, to discharge the ransom which the money represented.[141]