Philadelphia -was thrown into a spasm of excitement tliis morning by an assault upon Col. Alex. MoOlure, editor of the mes, by Nat McKay, whom tlie Times lias repeatedly denounced as a plundering naval contractor. The assanlt took place on Che&tnut street in the middle'of the day, when that thoroughfare was thronged with people. Col. McClure ■was walking along with ex-Gov. Curtin, cntirely without apprehension of danger. Neither of them noticed the stalwart form of McKay until he liad come square up nlongside of Col. McClure. His face flushed and paled as he said, with some profanity: " I will settle with you now, myself." As he spoke he drew from his breast a small plaited leather whip, and drew it to strike Col. McClure, but his awkwardncss and cowardice sö unnerved him, even with two hired ruffians at his hecls, that, before he could bring his whip down, Col McClure sprang upon him, seized him firmly by the throat with both hands, and held him ns if in a vise. McKay gagged and struggled to extricate himself, but in a few seconde it was manifest that he was entirely helpless, and that he must speedily f all at the mercy of the man ho had assailed. All this was the work almost of an instant, and the two hired "pais " of McKay at onco rushed in upon Col. McClure, and, in loss time than it could bo told, one who gives his name at the mngistrate's as John Conlan struck McClure a strong blow on the back of the head and f ollowed it with another on the lolt ear. A passing citizoi: seized the fellow called Conlan and held him from further blows. While Conlan was striking Col. McClure from behind nnother "pal" of McKay rushed tipoñ Col. McClure in front and struck him over the left oye with some instrument, probably a blackjack, and was about to repeat the blow when he was thrown back by ex-Gov. Curtin, and in the crowd he made his escape without being identifled by any one present. In the meantime Col. McClure held McKay by the throat until he was released by the interference of the crowd and the officers. McKay and the so-called Conlan were taken in enstody by the pólice, -who asked Col. McClure what he wantod done with them. He answered that the hired ruffians should be held, but that he could settle the matter with McKay. It is evident that MoKay had worked his eourace ut to an attempt to whip McCmre, bclieving that, as he was niucli the more rtlgged of the two, he ould master Col. McClure and degrade üm by at public whipping, but, consultng his fears, he employed two ruffians to id him in case he ahould f ail, and thus ave himself f rom getting flogged instead i flogging the hated editor, His one ttendant, who giveshis name as Oonlan, s a New York rough, with his profesional card covering his -whole face. He was unnoticed in the affair until he neaked up behind Ooi. McClure and truck two rapid blows on the back of he head and ear. It is evident, also, ;hat thieving was one of the purposes of UcKay's "pais," as ex-Gov. Ourtin's watch-chain was torn from him and Col. "tfcClure's was torn off also, and neither of them had been in a position to have their chaina taken by accident, and he fact that neither of their chains were ound proves that they were taken by ,he thieves. Both saved their watches jy the neck-chains breaking a few links rom the stem.