Very different is the state of those streets nowadays. Long after the hour when the electric trams have ceased from troubling and the motor omnibuses are at rest, the heavy road transport from the country thunders through the streets; the air is rent by the howls of the electric hooter, and belated motor-cyclists fly past, stuttering explosively like perambulant Lewis guns with an inexhaustible charge. “Let us get into the by-streets,” said Thorndyke, as a car sped past us uttering sounds suggestive of a dyspeptic dinosaur. “We don’t want our conversation seasoned with mechanical objurgations. In the back-streets it is still possible to hear oneself speak and forget the march of progress.” We turned into a narrow by-way with the confidence of the born and bred Londoner in the impossibility of losing our direction, and began to thread the intricate web of streets in the neighbourhood of a canal. “It is a remarkable thing,” Thorndyke resumed anon, “that every new application of science seems to be designed to render the environment of civilized man more and more disagreeable. If the process goes much farther, as it undoubtedly will, we shall presently find ourselves looking back wistfully at the Stone-age as the golden age of human comfort.” At this point his moralizing was cut short by a loud, sharp explosion. We both stopped and looked about from the parapet of the bridge that we were crossing. “Quite like old times,” Thorndyke remarked. “Carries one back to 1915, when friend Fritz used to call on us. Ah! There is the place; the top story of that tall building across the canal.” He pointed as he spoke to a factory-like structure, from the upper windows of which a lurid light shone and rapidly grew brighter. “It must be down the next turning,” said I, quickening my pace. But he restrained me, remarking: “There is no hurry. That was the sound of high explosive, and those flames suggest nitro compounds burning. _Festina lente._ There may be some other packets of high explosives.” He had hardly finished speaking when a flash of dazzling violet light burst from the burning building. The windows flew out bodily, the roof opened in places, and almost at the same moment the clang of a violent explosion shook the ground under our feet, a puff of wind stirred our hair, and then came a clatter of falling glass and slates. We made our way at a leisurely pace towards the scene of the explosion, through streets lighted up by the ruddy glare from the burning factory. But others were less cautious. In a few minutes the street was filled by one of those crowds which, in London, seem mysteriously to spring up in an instant where but a moment before not a person was to be seen. Before we had reached the building, a fire-engine had rumbled past us, and already a sprinkling of policemen had appeared as if, like the traditional frogs, they had dropped from the clouds.