Translation:I ate the porridge right away, and the orange an hour later.
i think your suggestion highlights why "i ate the porridge right away and the orange in an hour" is not only awkward, but probably wrong! If "i ate the porridge right away and the orange one hour later", then i would understand this as both having taken place in the past (e.g. porridge 2 hours ago and apple 1 hour ago). But "in an hour" is in my understanding used for something which will happen in the future (e.g. porridge 6 minutes ago, apple in one hour). But the Russian sentence has only one verb, and it is in the past tense. And maybe worth noting the verb isn't only in past tense, but perfective as well.
It's a bit semantically awkward. Usually "in an hour" is either used with the future (as discussed) to specify a time: "I will help you in an hour", or to indicate how long the activity will take: "He did it in an hour". If you mix these you can create ambiguity, such as: "I can do it in an hour". What's meant is sometimes clear from context, but not always.
Your sentence would be better if you said "...after an hour". It seems to me через can be translated with either "in" or "after", but in this case the latter is better.
I'll reply here so the indenting doesn't get out of control. «после» is "after" in the sense of "the period of time after something", e.g. "«после час» is "after one o'clock". «через» is "after" in the sense "after the specified period has elapsed, starting from now unless specified", so «через час» is "an hour from now". English uses the same word for both concepts; Russian does not. Wiktionary has a good example: «че́рез семь мину́т по́сле отхо́да» = "seven minutes after departure".
Wiktionary is an excellent resource:
Would a native speaker care to comment?
(Recovered comments) 1: Straight away and right away - is there any differences?
2 AndroidKanada: Not in meaning: "straight away" is British, "right away" is American.
Not to be confused with the noun "straightaway" of course. ( Or a right-of-way. (
1: Thank you, friend.
BTW, my Yandex translator doesn't know the noun "straightaway". What is the difference between "straight away" and "straightaway"?
2 AndroidKanada: A straightaway is a straight section of a race course.
П.С. The British will sometimes spell the adverb phrase without the blank: "I will answer straightaway." But context should make it clear which it is.
1: Thank you, I got it.
This is in reply to this comment here. It is posted here because it is too long for that level of indent.
Good question, Anatbst. I just don't think Russians use "после час" all that often. But before I go any further, I do believe that if you're referring to "one o'clock" with после час, "час" declines to ча́са (because после takes genitive case, not accusative like через). Whether you search for после час or после часа, this Google Ngram indicates neither is used all that often:
To enlarge the image, bring it up in Chrome, right click the image, and open it in a new tab.
In the examples I have seen of после час, it looks as if it is used as an adjective-noun construct such as "after hours care."
As for specific differences between после часа, and через час, it looks like it's just the difference between saying "after an hour" and "in an hour." These two phrases also have different frequencies in English:
As I think someone may have mentioned earlier, one makes a reference to a past action and the other to the future, but I think that partially explains the addition of the em dash (—).