Specific performance — time and impossibility

Although the covenant to convey is not a condition precedent on the performance of which the covenant to build depends, yet both from the words of the contract and the nature of the transaction, it was apparently the expectation of the parties that the conveyance would precede the building. . . . equity cannot relieve where it is impossible to place the parties in the same situation, and when real fault is imputable to the person praying the aid of the Court.