"If you are asking what a monetary value in the past is "worth" today, there is no one correct answer. A price or an income in the past would have been valued in different ways in that time by different people and under different contexts. That must be taken into account when asking the same question today." (taken from Measuring Worth).
An excellent introduction to the nature of the question "what is money worth?" In this short and flowing article (which everyone should read before scrolling any further down the page!), John Steele Gordon uses the varying fortunes of a mansion and a pearl necklace from the turn of the 20th century to illustrate how money was very different in the past than it is today. Gordon outlines a number of rules for thinking about historical currencies:
- Inflation is seldom the whole answer
- The law of supply and demand is always in operation
- It’s not the dollar cost that’s important, it’s the percentage of income
- Money isn’t everything, even in economics
- One technology replaces another only because it is cheaper or better or both
- The real cost of human labor has risen steadily since the Industrial Revolution
Compiled by former Exeter University librarian Roy Daves, this listing of dozens of internet sites is aimed at answering the question: "How much would X amount of money be worth today?" Many of the websites in this collection concern the UK, with the US being a distant second. In general however there's a good level of diversity, and while most sources deal with the 20th century there are a few which look as far back as the Middle Ages.
One of the most impressive and well-researched websites I've located, Measuring Worth offers historical comparisons of the pound, dollar, yuan, and yen among many other calculating services. Furthermore, it provides complicated answers to what you might assume are simple questions: if you ask for a conversion between 1800 and 2009 dollars, you'll end up with over 5 different answers, each of which takes into account a different economic aspect (purchasing power, % GDP, average salary, etc.).
This PhD dissertation by Carol Albrecht is a broad survey of the state of music in Vienna around the turn of the 19th century. Most pertinent for our purposes is her Appendix A (on page 231), which lists the salaries in florins of the members of the Vienna Hoftheatre for the year 1799-1800.
An indispensable table for understanding the German, French, English, Spanish, and Portuguese currencies of the time. Dr. Robert Selig provides a breakdown of the units in each currency (e.g. for the English: pound sterling, souvereign, guinee, crown, shilling, penny, ha'penny, farthing), then offers some approximate exchange rates. Also includes some notes on the variety of currencies in use in the American colonies.