Read large '.csv' files from zipped file

Hi all,
    I use ireadLines function to iterate large '.csv' files from '.zip' file. When I execute the nextElem function in R console, I can only fetch the first line of file content no matter how many times . Example code show as bellow.

library(iterators) 
con<-unz(description='g:\\hourly_WIND_2013.zip',filename='hourly_WIND_2013.csv') 
it<-ireadLines(con) 
nextElem(it) 

[1] "\"State Code\",\"County Code\",\"Site Num\",\"Parameter Code\",\"POC\",\"Latitude\",\"Longitude\",\"Datum\",\"Parameter Name\",\"Date Local\",\"Time Local\",\"Date GMT\",\"Time GMT\",\"Sample Measurement\",\"Units of Measure\",\"MDL\",\"Uncertainty\",\"Qualifier\",\"Method Type\",\"Method Name\",\"State Name\",\"County Name\",\"Date of Last Change\""

nextElem(it) 

[1] "\"State Code\",\"County Code\",\"Site Num\",\"Parameter Code\",\"POC\",\"Latitude\",\"Longitude\",\"Datum\",\"Parameter Name\",\"Date Local\",\"Time Local\",\"Date GMT\",\"Time GMT\",\"Sample Measurement\",\"Units of Measure\",\"MDL\",\"Uncertainty\",\"Qualifier\",\"Method Type\",\"Method Name\",\"State Name\",\"County Name\",\"Date of Last Change\""

Can anybody tell me what did i missed?

Regards



Jianwen Luo