I think it's used to convey that the buying power has been reduced. If you have a $100 basket of goods (as measured in 1914 dollars), $100 in 1914 allows you to buy 1 basket of goods. Due to the devaluation, today spending $100 would only give you a $3.05 basket of goods (as measured in 1914 dollars).

It's a bit of an odd comparison since you're using two different units for dollars to compare the basket vs purchasing dollar. The clearer way to say it is that today's $100 basket of goods is equivalent to $3.95 basket of goods of 1914.