reflexive pronoun and to infinitive

[jennie77]

1. Island fishermen use the movements and activities of seabirds to aid them in navigation and finding fish.

In the sentence above, them seems a little akward.
Shouldn't it be "themselves" instead of them, for them here points the fishermen themselves. (They (Fishermen) aid themselves (fishermen) in nevigation and findind fish using the movements and activities of seabirds."

Or in another case, can to infinitive here be seen to modify noun " the movements and activities of seabirds"?
Then, them here seems OK, for the movements and activities of seabirds actually aid the fishermen (them) in navigation and finding fish.

2. By 1910, the racetyracks and expensive hotels had closed down as the wealthy found other playgrounds to inhabit.
By the late forties, the public seemed to lose interest in the joys that Coney Island offered.
By 1960, attendance was so low that fifty acres of the resort were demolished for high rise apratment buildings.

All of three sentences have by ~ , the the tenses are different.
The first one uses past perfect, but the rest two use simple past.
Is there any reason that there is a difference in tense?

Which one is right?
Thank you in advance.

[Marius Hancu]

Better, IMO:

Island fishermen use the movements and activities of seabirds as (means of) assistance in navigation and finding fish.

Island fishermen use the movements and activities of seabirds as help in navigation and finding fish.

Island fishermen use the movements and activities of seabirds in order to help themselves in navigation and finding fish.

or simpler:

Island fishermen use the movements and activities of seabirds in navigation and finding fish.

[OddThomas]

Themselves would have been a better choice, grammatically, but apparently them was easier. (We are not required to use a reflexive form.) As you have discovered, them raises questions about antecedent--which them, the fishermen or the birds? A good compromise would have been to delete them altogether. I object also to making the noun navigation parallel with the participle finding. I would prefer the gerund finding much more. So I propose this:Island fishermen use the movements and activities of seabirds to aid in navigation and fish finding.

Next, the past perfect is necessary in the first of your three sentences because of the sequential timing of the closing after the finding of other playgrounds. Note that the word as is tricky. If the past tense is used, the impression is that the wealthy found other playgrounds at the same time as the closing. If the past perfect is used, then the racetracks and hotels closed after the wealthy had gone. In the remaining two sentences, the simple past is fine because of the straightforward narrative aspect of the sentences. In the third sentence, I see low attendance and demolition as contemporaneous events.

[Pete]

1. Island fishermen use the movements and activities of seabirds to aid them in navigation and finding fish.

In the sentence above, them seems a little akward.
Shouldn't it be "themselves" instead of them, for them here points the fishermen themselves. (They (Fishermen) aid themselves (fishermen) in nevigation and findind fish using the movements and activities of seabirds."

...
I think it has to be them, not the reflexive themselves, even though the pronoun in question definitely has the subject of the sentence (fishermen) as its antecedent. Every grammar reference I checked that mentioned reflexive pronouns at all said to use the reflexive when the direct or indirect object of a verb is the same as the subject of the same verb. That can't be the whole story, since certainly we also use the reflexive with the objects of prepositions when the prepositional phrase is a complement of a verb and the subject of that verb is the antecedent of the object of the preposition. (For example: "Joe looked at himself in the mirror.") The verb might be an a conjugated (finite) verb or some other verb form with a real or implied subject. But it does seem that in a subordinate clause or with some other verbal construction, we use a reflexive pronoun for an object only if the subject of the verb in that construction is the antecedent of the pronoun. Said another way, once we are looking at a complement of a verb other than the main verb, simply having the subject of the sentence as an antecedent is not enough to cause a pronoun to be reflexive. Some sentences that help illustrate the various cases might be:
- Joe usually shaves himself.
- Joe likes [Joe, implied subject of the following infinitive] to shave himself on workdays.
- He likes a barber to shave him on Saturdays.
- Mary thinks the barber does a sloppy job; she likes Joe to shave himself.

2. By 1910, the race tracks and expensive hotels had closed down as the wealthy found other playgrounds to inhabit.
By the late forties, the public seemed to lose interest in the joys that Coney Island offered.
By 1960, attendance was so low that fifty acres of the resort were demolished for high rise apratment buildings.

All of three sentences have by ~ , the the tenses are different.
The first one uses past perfect, but the rest two use simple past.
Is there any reason that there is a difference in tense?

Which one is right?
Thank you in advance.
All three are correct. Note that the last two have verbs that describe a state of being, a situation that is true over a period of time, at a whole range of instants. In particular, it is true at the mentioned time, a time that is in the past when the statement is being made. Thus the simple past is appropriate; the time of "seemed" includes "the late forties", and the time of "was" includes "1960".

In the first sentence, the verb "closed down" is different; it refers to a specific act that took place at a particular time. Since that time must have been earlier than the past time that was mentioned, "1910", we use the past perfect tense for that sentence.

This is more than you asked, but sometimes you have to pay attention to the "lexical" category of a verb in order to pick the right tense. The lexical categories are:
1. activity (has duration) -- has no inherent beginning or ending -- run, live, study
2. accomplishment (has duration) -- no inherent beginning but has a definite well defined end -- write (a letter), make (a table)
3. achievement (punctual) == have a well defined end point, but no duration -- realize (something), find (something)

** Note: these first 3 lexical categories involve a change of some kind.

4. state -- describes a stable situation that we can presume will continue more or less indefinitely -- have, seem, want

When you see what appear to be similar sentences, presumably correct, that have different tense structures, it is possible or maybe even likely that the difference is caused by a difference in the lexical categories of the verbs in question. For example, in your first sentence, "closed down" is an "achievement" verb; in the other two sentences, the verbs are "state" verbs.

[Bridget]

Island fishermen use the movements and activities of seabirds to aid in navigation and fish finding.

I haven't found many examples of "fish-finding/fish finding" without a following noun.

There's fish-finding/fish finding: technology,equipment, apparatus, systems, etc., but used alone, it doesn't appear common.

As you have discovered, them raises questions about antecedent--which them, the fishermen or the birds?

Not at all. Imagine:

?! Island fishermen use the movements and activities of seabirds to aid those seabirds in navigation and finding fish.

More nonsense than even Edward Lear could conjure, right?