The question in this case is a narrow one. The plaintiff, being the lessee of an entire building, sublet a part of it to the defendant by a written lease containing the following clause: “ The lessee agrees to pay extra for steam heat at the rate of forty cents per foot of radiating surface " yearly.” It is agreed that the word “ extra ” means in addition to the rent reserved in the lease. It is also agreed that when the lease was made and when the defendant entered upon the premises, there were one thousand and seventy-seven square *374feet of radiating surface; and the plaintiff seeks to recover at this rate. The defendant has removed several of the radiators, and contends that it is liable to pay only for so much radiating surface as is reasonably necessary to heat the building.

We are of opinion that the plaintiff’s contention is the correct one. The terms of the contract are very plain and explicit. The sum is to be paid yearly, although of course during a portion of the year no steam heat would be necessary. The rate per foot is fixed, and what the radiating surface was when the lease was made was capable of computation. The lessee might use the whole radiating surface or as much as it saw fit, but under the agreement it must be held to pay for the entire radiating surface.

The evidence as to the amount of radiating surface reasonably necessary to heat the building was, therefore, properly excluded.

Exceptions overruled.