Page:Popular Science Monthly Volume 16.djvu/147

 gives the following account of the experiment made to test the efficacy of this method of employing petroleum in place of coal: "The little steamer Billy Collins was selected by Mr. Campbell for the test. A preliminary blaze of wood under the boiler raised the small quantity of steam necessary to start the burner into operation. The oil-valve was opened a trifle, the steam valve ditto. The petroleum trickled into the feed-pipe, was caught up by the steam, and both plunged into the depths of the fire-box, a mass of many-tongued, roaring, brilliant flame. As the pressure of steam increased, this flame grew in fury and intense heat. The needle of the steam-gauge climbed rapidly up the dial, and in twenty minutes the safety-valve blew off at 120 pounds pressure. . . . To ocean-going steamers this device must prove of extraordinary interest. A tank of oil, situated at a remote end of the ship, would hold fuel sufficient for a double trip, and supplant the great coal-bunkers with their attendant dirt."

What Nordenskjöld has done.—A current misapprehension of the work done by Nordenskjöld (pronounced Nordenshuld), in his recent memorable voyage, is corrected by the "Pall Mall Gazette." He is supposed to have discovered the "Northeast Passage." He has discovered nothing, not even the shore along which he sailed. Every part of his route was known before, and the whole coast-line had been laid down by the expeditions which, for more than three hundred years, have penetrated from the east and west, or, descending the great Siberian rivers, have crept along the European and Asiatic arctic shores in boats or in dog-sleds. What Nordenskjöld has actually done is to have sailed, in one continuous voyage and in one ship, from the Atlantic to the Pacific, and to have made en route a series of scientific collections and observations such as no other explorer in these seas—unless, perhaps, himself in former voyages—had been able to carry away. Professor Nordenskjöld is sanguine that he has proved the feasibility of the northeast passage for ships during most seasons. This the "Pall Mall Gazette" pronounces too hopeful a view, and assuredly a passage which requires over twelve months for its accomplishment can hardly be called "feasible" in any remunerative sense. But one thing is made clear by this voyage, namely, that the great Siberian rivers drive the ice off the coast during several of the late summer and autumn months, and that the Yenisei and Obi may be reached during average years. So confident is the Prussian Government that the products of their Asiatic empire will find their way to European markets by way of the Siberias rivers and the Arctic Sea, that they have already established custom-houses at the entrance to the Yenisei and the Obi.

Effects of Tobacco on the Teeth.—Habitual users of tobacco will draw some comfort from observations made by the author of a paper read before the Odontological Society of London. This writer, Mr. Hepburn, says that the direct action of nicotine on the teeth is decidedly beneficial. The alkalinity of the smoke must necessarily neutralize any acid secretion which may be present in the oral cavity, and the antiseptic property of the nicotine tends to arrest putrefactive changes in carious cavities. The author is inclined to believe that the dark deposit on the teeth of some habitual smokers is largely composed of the carbon of tobacco-smoke. This deposit takes place exactly in those portions where caries is most likely to arise, and on those surfaces of the teeth which escape the ordinary cleansing action of the brush. That tobacco is capable of allaying to some extent the pain of toothache is, he thinks, true—its effect being due not only to its narcotizing power, but also to its direct action on the exposed nerve; and he is inclined to attribute the fact of the comparatively rare occurrence of toothache among sailors in great measure to their habit of chewing.

Distribution of Luminous Power in the Sun's Rays.—With the aid of a new spectrometer based on the optical principle that a light becomes invisible when it is in presence of another light about sixty-four times more brilliant. Professor J. W. Draper has been enabled to prove that all the rays of the sun's light possess the same luminous power. In the prismatic spectrum the luminous