Not to make any alterations or additions to the Premises without prior consent in writing of the Lessor. Any and all major alterations or additions made by the Lessee to the Premises with or without consent of the Lessor shall become the property of the Lessor. And if the Lessee does so without such consent, he must, if on the request of the Lessor, restore the Premises to the former condition, and is liable to the Lessor for any loss or damage that may result from such alteration or addition.