1. **State the problem:** Calculate the voltage drop across resistor $R_1$ in the given circuit where $V_1 = 30V$ is measured across $R_1$ and the voltage source is $17V$. 2. **Analyze the circuit:** The circuit shows a voltage source of $17V$ connected in series with two resistors $R_2$ and $R_1$. The voltage $V_1$ across $R_1$ is given as $30V$. 3. **Check for consistency:** Normally, the voltage drop across a resistor in series cannot exceed the source voltage. Since $V_1 = 30V$ is greater than the source voltage $17V$, this suggests either a measurement or labeling error in the problem statement. 4. **Assuming the problem wants the voltage drop across $R_1$ as $V_1$:** The voltage drop across $R_1$ is already given as $30V$. 5. **Conclusion:** The voltage drop across resistor $R_1$ is $\boxed{30V}$ as per the measurement $V_1$. If the problem intended to find $V_1$ from the circuit values, more information about resistances or current would be needed.