I was trying to date some old bottles in my collection and ran into a bit of problem. Although I do read and write traditional Chinese, the old Chinese calendar with which years were organized, named Sexagenary cycle, make it impossible to associate the value to the Western calendar that we all understand. For example, on a Zhou Leyuan bottle, he might date it the year 壬辰, which actually corresponded to the year 1892.
Luckily, our good friends at wikipedia, have created a page so that you can look up the mapping values. This is the URL:
http://zh.wikipedia.org/wiki/%E5%B9%B2%E6%94%AFThis page is in Chinese so for non-Chinese reader it can be difficult. There is, however, a table listed with all the possible values in the Chinese system (there are in total 60). At this point you may ask how can 60 values be enough to represent all the years from AD1 to AD2011. The fact is it cannot. In the old days, after 60 years the same name will be reused. For example, in the example above, 壬辰 is 1892, but it can also be 1832 or 1952. We know the date must be 1892 because that is the only logical choice.
Going back to how to use the page. You can normally be able to identify the two characters on the bottle associated with the year (if not then you are out of luck). After you identify it, click on that value on the table. It will bring up another table that give you the possible Western calendar year corresponding to that year. Then you can deduce the correct year based on the period with which the artist was active. Luckily so far there was no artist that has career spans more than sixty years!
Hope this will help for you to understand more about your bottles and probably authenticate them.