Hence we had to transport compasses to different parts of the ship, take many readings, and strike an average.

所以，这样就必要对于挪到船上各部分的罗盘做很多的观察，拿一个平均数作标准。

Yet nowhere can quite compare with Lake Maracaibo, where lightning strikes an average 250 times per square kilometer, giving it the highest lightning density of any place on Earth.

但是没有一个地方 可以和马拉开波湖相提并论，那儿的闪电的次数 达到每平方公里250次，是地球上闪电密度最高的地方。