British scientist and inventor Barnes Wallis had been asked to produce a bomb that could destroy these bunkers. The resulting bomb weighed 12,000 pounds, and if dropped from 20,000 feet would penetrate the earth and cause a small scale earthquake, destroying the target. He called this bomb the Tallboy. To be effective the bombs had to be dropped very accurately. He stated that, for accuracy requirements, one bomb out of fifteen dropped from 20,000 feet needed to land within twelve metres of the target. This was an accuracy unheard of in daytime aerial bombing, let alone bombing at night. Cheshire suggested this was going to be a problem, but got no sympathy from Wallis, who replied "Well, if you're going to scatter my bombs all over northern France what's the point of my building them?"