All participles are compound in their meaning and office.  Like verbs, they express action and being, and denote time; and, like adjectives, they describe the nouns of which they denote the action or being.  In the sentences, The boatman is crossing the river; I see a man laboring in the field; Charles is standing; you perceive that the participles crossing and laboring express the actions of the boatman and the man, and standing the state of being of Charles.  In these respects, then, they partake of the nature of verbs.  You also notice, that they describe the several nouns associated with them, like describing adjectives; and that, in this respect, they participate the properties of adjectives.  And, furthermore, you observe they denote actions which are still going on; that is, incomplete or unfinished actions; for which reason we call them imperfect participles.

Perhaps I can illustrate their character more clearly.  When the imperfect or present and perfect participles are placed before nouns, they become defining or describing adjectives, and are denominated participial adjectives; as, A loving companion; The rippling stream; Roaring winds; A wilted leaf; An accomplished scholar.  Here the words loving, rippling, roaring, wilted, and accomplished, describe or define the nouns with which they are associated.  And where the participles are placed after their nouns, they have, also, this descriptive quality.  If I say, I see the moon rising; The horse is running a race; The dog is beaten; I describe the several objects, as a rising moon, a running horse, and a beaten dog, as well as when I place these participles before the nouns.  The same word is a participle or a participial adjective, according to its manner of meaning.  The preceding illustration, however, shows that this distinction is founded on a very slight shade of difference in the meaning of the two.  The following examples will enable you to distinguish the one from the other.

Participles.  Participial adjectives.

See the sun setting.  See the setting sun. 
See the moon rising.  See the rising moon. 
The wind is roaring.  Hear the roaring wind. 
The twig is broken.  The broken twig fell. 
The vessel anchored in the The anchored vessel spreads
  bay, lost her mast. her sail.