what is the difference between the two sentences

[Babai]

1.''The dog sat watching in front of the house.''

2.''The dog sat to watch in front of the house.''

Do the two sentences above express same meaning? do these sentences express reason or cause? is the sentence ''the dog sat watching.........'' a participle here and works as a adverb expressing cause or reason? please explain grammatically.Thank you.

[bhaisahab]

1.''The dog sat watching in front of the house.''

2.''The dog sat to watch in front of the house.''

Do the two sentences above express same meaning? do these sentences express reason or cause? is the sentence ''the dog sat watching.........'' a participle here and works as a adverb expressing cause or reason? please explain grammatically.Thank you.

Neither sentence is natural English. We would most likely say, "The dog sat on watch at the/in front of the house."