What is the part of speech is "on" in the phrase "A few miles further on"?
There is an example sentence:
We found a secluded beach a few miles further on.
In this sentence, I referred to the dictionary and found that the part of speech of further is an adverb. However on is given both as a preposition and an adverb, with very many definitions.
In addition, this post suggests that we shouldn't rely on dictionaries too much for grammatical information anyway.
The answers and comments below give responses from trusted users which give opposing analyses—some indicating on is an adverb here and some saying it is a preposition.
So I can't figure out that what the part of speech of on is. Secondly what is the meaning of on in this sentence?
I think that 'on' is not a preposition, because there is no noun or noun phrase that could go with it. It must be an adverb. Cambridge Dictionary gives you this:
on, adverb (MOVING FORWARD), continuing forward in time or space: They never spoke to each other from that day on (= after that day).
Both in your example and in that provided by Cambridge Dictionary, the sentences would mean the same thing and be correct as well. The 'on' doesn't so much mean something definite as it adds a certain emphasis to the adverb/adverbial phrase further/from that day that it modifies, underlining an aspect of progression.
Further on is a compound adverb. It makes no sense to ask what part of speech on is in this context.
Collins Cobuild English Grammar (p303) has other examples in the section on adverbs of position:
'Deep down', 'far away', 'high up', and 'low down' are often used instead of adverbs on their own.
- The window was high up, miles above the rocks.
- Sita scraped a shallow cavity, low down in the wall.
'Far' and 'far way' are often qualified by a prepositional phrase beginning with 'from'.
Google has numerous examples of the adverb 'further on' followed by a prepositional phrase beginning with from. For example:
- further on from the hotel
The word "on" by itself is a preposition. " Further" is an adverb. Together, "further" and "on" make a prepositional phrase which I think works as an adjective here since it refurs to "miles".