A was aware that B was set to expand his firm. He decided to write to B and offer his machine for $. He specified that he must have B's reply by...

A was aware that B was set to expand his firm. He decided to write to B and offer his machine for $. He specified that he must have B’s reply by ‘return mail’. B immediately posts his acceptance. Normally the letter would have arrived within a day or two but because of post's industrial action, the letter did not reach A until over 10 days later. In the meantime, however, A offers the machine to another firm in the area owned by C for $ and does not wish to sell to B at all as he feels that C will pay more.  Can B enforce the contract with A?