When visiting the senate chamber during session, who will be presiding over the session

Although the Constitution states that the Vice President is vested with the power to preside over the Senate, the Vice President is often not in attendance. Instead the "pro tempore" presides over the Senate when the Vice President is not present and typically those presiding over the Senate are junior Senators. 

Currently, as of february 2016, an american traveling in france would be by the exchange rate. the weakness of the euro and the strength of the us dollar means that items in france cost less to an american than they otherwise would. of course, if this trend reverses and the us dollar weakens and the euro strengthens, such as was happening in early 2008, an american traveling in france would have an adverse experience because items would cost relatively more.