I pointed out to him that we were miles away from a pub (я обратил его внимание, что мы находимся на расстоянии /многих/ миль от трактира); and then he went on about the river, and what was the good of the river (и он набросился на реку: какая польза от этой реки), and was everyone who came on the river to die of thirst (и /неужели/ всякий, кто отправился на реку, должен умереть от жажды)?

It is always best to let Harris have his head when he gets like this (всегда лучше не мешать Гаррису, когда он становится таким). Then he pumps himself out, and is quiet afterwards (потом он выдыхается и /становится/ тихим; to pump — выкачивать).

I reminded him that there was concentrated lemonade in the hamper (я напомнил ему, что в корзине есть концентрированный лимонад), and a gallon-jar of water in the nose of the boat (и галлонный кувшин воды на носу лодки), and that the two only wanted mixing to make a cool and refreshing beverage (и что эти два /вещества/ требуется лишь смешать, чтобы получить прохладный и освежающий напиток).

concentrated ['knsntretd] beverage ['bevr]

I pointed out to him that we were miles away from a pub.; and then he went on about the river, and what was the good of the river, and was everyone who came on the river to die of thirst?

It is always best to let Harris have his head when he gets like this. Then he pumps himself out, and is quiet afterwards.

I reminded him that there was concentrated lemonade in the hamper, and a gallon-jar of water in the nose of the boat, and that the two only wanted mixing to make a cool and refreshing beverage.

Then he flew off about lemonade (он налетел на лимонад; to fly), and "such-like Sunday-school slops (и подобную бурду для воскресной школы)," as he termed them, ginger-beer, raspberry syrup, etc (как он их назвал, имбирное пиво, малиновый сироп и т.д.). He said they all produced dyspepsia, and ruined body and soul alike (сказал, они все вызывают расстройство пищеварения, а также разрушают тело и душу), and were the cause of half the crime in England (и являются причиной половины преступлений в Англии).