 The terms were not uncertain, nor were the parties uncertain, and it should be clear that people who lawfully acquired a smokeball could benefit.There would be no reason for a limitation to people who got the smokeball as a gift, because an increased sale being a benefit to the defendants, though effected through a middleman, and the use of the balls must be presumed to serve as an advertisement and increase the sale.The amount of time the smokeball should last (and the company be bound by) was a matter of construction, of which several were possible (a fortnight, till the flu epidemic ends).