scrape the bottom of the barrel刮桶底

Winds blow ships from Africa to the Indies naturally, as if the route were blessed by God. Another argument in defence of the trade is that the Newfoundland fishing industry is kept afloat by the fact that slaves in the West Indies consume that part of the fish which is fit for no other consumption. I do feel that if my honourable friend continues to scrape the bottom of the barrel for objections, he is in danger of getting splinters under his fingernails. Now, if I may continue with my argument... As representative of the great and flourishing commercial town of Liverpool, I must once again remind the House that we have no evidence that the Africans themselves have any objection to the trade.

风自然地把船从非洲吹到西印度群岛，仿佛这条航线受了上帝的保佑。 为这项贸易辩护的另一个理由是：纽芬兰的渔业能维持下去，全靠西印度群岛的奴隶吃掉那些别人没法吃的鱼。 我真心觉得，要是这位尊敬的朋友还继续把桶底刮干净来找反对理由，只怕木刺要扎进他指甲缝里了。 那么，请允许我继续我的论证…… 作为繁荣兴旺的商业重镇利物浦的代表，我必须再次提醒议会：我们没有任何证据表明，非洲人自己对这项贸易有任何反对。

My honourable friend, the member for Liverpool, seeks evidence of people's concern. In the past year, I and my itinerant clergymen friends have been gathering just such evidence. We have taken a petition calling for the abolition of the slave trade to all the great cities of this country. It has been signed by over 390,000 people. However, this petition is not yet complete. There is one more person who wishes to add his name.

我这位尊敬的利物浦议员，想找民众关心的证据。 过去一年，我和我那些四处奔走的牧师朋友们，一直在搜集的正是这类证据。 我们把一份呼吁废除奴隶贸易的请愿书，带到了这个国家所有的大城市。 上面有三十九万多人签名。 不过，这份请愿书还没有完成。 还有一个人，想把自己的名字添上去。