A piece of glowing charcoal, kept hot by the bellows, would not produce an explosion when surrounded by dust, but when fanned into a blaze the explosion followed. A common kerosene lantern, when surrounded by dust of all degrees of density, would not produce an explosion, but when the dust was blown into the bottom, through the globe and out of the top, it would ignite. To explode quickly the dust must be dry. Evidently when an explosion has been started in a volume of dusty air, loose flour maybe blown into the air and made a source of danger. * * * * * =New Engineering Inventions.= Erskine H. Bronson, of Ottawa, Ontario, Canada, has patented an improvement in Automatic Switches for Railways, which consists in an arrangement of sliding cams for moving the switch rails, and in treadles to be operated by the pilot wheels of the locomotive, and in intermediate mechanism for connecting the treadles with the switch operating cams, the object being to provide a switch will be operated by the pilot wheels of the locomotive as it approaches the movable switch rails. An improved Refrigerator Car has been patented by Michael Haughey, of St Louis, Missouri. The object of this invention is to ventilate and cool railway cars used in the transportation of perishable articles. This car has a novel ventilator and ice box and is provided with a new form of non-conducting walls. * * * * * =CROOKED JOURNALISM.= In the English scientific journal _Engineering_, of June 21, 1878, appears a six column article on "Edison's Carbon Telephone," illustrated with ten engravings from Mr. Prescott's recent work on "The Speaking Telephone, Talking Phonograph, and other novelties." The descriptions of the cuts, and the rest of the information given, so far as correct, obviously come from the same source. So far as correct: unhappily for the honor of scientific journalism, the writer's desire is plainly not so much to do justice to truth as to exalt Mr. Hughes at the expense of Mr. Edison. To this end he has studiously suppressed from Mr. Prescott's description of the carbon telephone the points which establish Mr. Edison's claim to the prior invention or discovery of everything involved in Mr. Hughes' microphone, while he has as studiously dwelt upon those same points as constituting the peculiar merits of Mr. Hughes' work. For example, while he uses Fig. 21 of Mr. Prescott's book, he leaves out the very important little diagram numbered 20. It represents one form of the apparatus to which Sir William Thomson refers in the letter in which he says: "It is certain that at the meeting of the British Association at Plymouth last September, a method of magnifying sound in an electric telephone was described as having been invented by Mr. Edison, which was identical in principle and in some details with that brought forward by Mr. Hughes."