“ On condition broken, they do not ipso facto lose all interest in the property and its proceeds. The contract does not contain the common stipulation that the tenant shall be compensated for his permanent improvements. On the tenant's default the city cannot at once enter into possession, but 'the lot and improvements shall be leased out at public outcry for the remainder of the term,' and after deducting unpaid rent and taxes, the overplus, if any, shall be paid to the lessees. ”

“ Where one relies upon an exemption from taxation, both the power to exempt and the contract of exemption must be clear. Any doubt or ambiguity must be resolved in favor of the public. St. Louis v. United R. Co. 210 U.S. 273, 52 L. ed. 1057, 28 Sup. Ct. Rep. 630. Here there is not only no language of exemption, but a positive agreement on the part of the lessees to pay public taxes on the land. In compelling them to do so, the contract is enforced instead of impaired. ”

“ The contract creates an estate somewhat like the perpetual lease of the civil law, where the tenant was for many purposes treated as owner, and liable for taxes. 10 Merlin Rep. p. 232; Cooper, Inst. 277, 278; Sohmn, Inst. 3d ed. 346. It was also similar in its nature to ground rent, where an annual rental and public taxes are perpetually charged on the land, instead of a gross sum being paid or secured. There the grantor is treated as having a fee in the rent reserved, and the grantee a fee in the land, subject, among other things, to the payment of public taxes. ”