r - Plot multiple curves in R

Question

A have 2 datasets

Summer 1 :

Time  Temerature
1          12,5
500        13,5
1000       15    
1500       16
2000        19
2500       20
3000       21

summer 2

Time  Temperature
1          12,5
500        13,5
1000       15    
1500       16
2000        19
2500       20
3000       21
3500       23
4000       34

I want to plot the 2 temperature curves (summer 1 and summer 2) according to the time in R. The problem here concerns the axis for the 2 datasets which are not the same : summer 1 (from 1 to 3000) and summer 2 (from 1 to 4000). Can you help me please?