In the north, where all was safe, the sky was fairly clear; but where the fire took its way the smoke haze hung grim and close. From the east the scene was a striking one. Along the water front of Fort Point Channel were the buildings gray and red; down Summer Street, which lay like a canyon between walls of brick and stone, white steam and smoke rode in a seething mist, lighted at odd times and places by keen flashes of crude red fire; over the roofs wavered more steam and smoke, floating in some places like level banners which flapped in the wind, while in others it seemed to wrap itself in dirty folds about some skeleton of what had yesterday been a building. At various points, and suggested by the premonitory roar of dynamite, rose black, sinister columns of the densest smoke mingled with the dust of shattered buildings, like the pictured outburst of some volcanic crater; and through and behind and implicitly within all this the Fire moved upon its way. It was about half-past seven in the morning when it was seen that all efforts to check the flames at Summer Street had failed. Along the north side of that thoroughfare lay the tumbled ruins of the dynamited buildings, destroyed in a hopeless hope, for the remedy had been too homeopathic and the disease too swift. Indeed, it almost seemed as though the razing of these structures had merely made more easy the progress of that river of unconsumed gases and air which the steady wind drove undeviatingly forward upon the windows and the roofs which the conflagration had not yet reached. It was very much as though this flood of invisible heat and destruction contained the sharp-shooters before an army's van; it was like the cavalcade that rode before a Roman Emperor's triumph two thousand years ago; like the flight of arrows which preceded the thunderous charge of English heavy soldiery on Continental battle grounds. In the little triangle between three streets just west of Dewey Square stood a solidly built, compact group of five- and six-story structures, one of them of fire-proof construction. This triangle, by a vagary, now proved to be a crucial point. If this could be saved, probably so also could the whole block to the south of Summer Street; but if it could not, then that block too was doomed, and there was grave danger beside lest the district east of Federal Street be also involved. So on this precious spot the combined forces of defense concentrated. In Fort Point Channel four fireboats gave their powerful pumps to aid the engines; the firemen, hanging close to their work, sent stream after stream of water against the attacking flame.