“Where Ufens glides along the lowly lands,
    Or the black water of Pomptina stands.”—­Dryden.

OBS. 23.—­In several phrases, not yet to be accounted obsolete, this old preposition a still retains its place as a separate word; and none have been more perplexing to superficial grammarians, than those which are formed by using it before participles in ing; in which instances, the participles are in fact governed by it:  for nothing is more common in our language, than for participles of this form to be governed by prepositions.  For example, “You have set the cask a leaking,” and, “You have set the cask to leaking,” are exactly equivalent, both in meaning and construction.  “Forty and six years was this temple in building.”—­John, ii, 20. Building is not here a noun, but a participle; and in is here better than a, only because the phrase, a building, might be taken for an article and a noun, meaning an edifice.[137] Yet, in almost all cases, other prepositions are, I think, to be preferred to a, if others equivalent to it can be found.  Examples:  “Lastly, they go about to apologize for the long time their book hath been a coming out:”  i.e., in coming out.—­Barclay’s Works, Vol. iii, p. 179.  “And, for want of reason, he falls a railing::”  i.e., to railing.—­Ib., iii, 357.  “That the soul should be this moment busy a thinking:”  i.e., at or in thinking.—­Locke’s Essay, p. 78.  “Which, once set a going, continue in the same steps:”  i.e., to going.—­Ib., p. 284.  “Those who contend for four per cent, have set men’s mouths a watering for money:”  i.e., to watering.—­LOCKE:  in Johnson’s Dict. “An other falls a ringing a Pescennius Niger:”  i.e., to ringing.—­ADDISON:  ib. “At least to set others a thinking upon the subject:”  i.e., to thinking.—­Johnson’s Gram.  Com., p. 300.  “Every one that could reach it, cut off a piece, and fell a eating:”  i.e., to eating.—­Newspaper. “To go a mothering,[138] is to visit parents on Midlent Sunday.”—­Webster’s Dict., w.  Mothering. “Which we may find when we come a fishing here.”—­Wotton. “They go a begging to a bankrupt’s door.”—­Dryden. “A hunting Chloe went.”—­Prior. “They burst out a laughing.”—­M.  Edgeworth. In the last six sentences, a seems more suitable than any other preposition would be:  all it needs, is an accent to distinguish it from the article; as, a.