Wages are one indicator of social class. Other factors used as measures of social class may include education, occupation, social status and power, and cultural norms.
There are books in the Society & Culture page which will help you learn more about the business/economic situation at the time of the play and some information about social class.
You are finding the approximate--not exact--salary of a minister to get a better sense of the social class/buying power of Reverend Harper and his daughter Elaine. Note that clergy salaries varied based on several factors: the denomination (e.g., Methodist, Congregationalist, Baptist, etc.), the relative wealth of the members of the parish/church, geographic region, urban/rural, etc.
Provides salaries of ministers from 1890-1926 in the pdf document Annual earnings in selected industries and occupations: 1890–1926.
1. Click on the blue "Search" tab in the upper right of the screen. In the search box, type -> salaries ministers
2. In the list of results, click on the link for the table "Annual Earnings in Selected Industries and Occupations: 1890-1926."
3. When viewing the table on the next screen, find the "Jump to" box at the top right of the table. Click on the blue arrow to get to column Ba4334 which is "Ministers." Scroll down the list of years until you see the salary for 1926.
*Note: if you look at the Series Ba4334 definition in the left sidebar, you will see the two sources for this data.
4. Then.....for the salary you find in both the print and online version of Historical Statistics, use that salary in the Consumer Price Index Calculator http://www.bls.gov/data/inflation_calculator.htm to roughly estimate what a minister's salary was in 1940/41.
Newspapers
Search the Brooklyn Daily Eagle newspaper to find articles that mention ministers' salaries. Type -> ministers salaries <- into the search box, or salaries clergy. After the search , use the date limit in the left sidebar to limit your search to : 1930-1940. July 18, 1933 page 7 (in search box, type: minister salaries) for some insight into how salaries were set for ministers. See this section "Everyday Questions" on page 19 from the Sunday February 21, 1932 issue. Also, ....
Sample Article: