Open main menu

Page:Popular Science Monthly Volume 2.djvu/659

This page has been validated.

com, and claim descent from white men. Masas is perhaps the same as Mashash, which occurs in the Egyptian documents applied to the Tamahus. The Masas wear the hair in the same fashion as the Tamahus, and General Faidherbe is inclined to think that they, too, are the descendants of the dolmen-builders.


Deep-Sea Photometer.—A deep-sea photometer, or instrument for measuring the chemical power of the solar ray at great depths in water, was shown at the late London Exhibition by Mr. C. W. Siemens. A roll of sensitive paper, hermetically closed in a glass tube, is placed in a thick disk attached to the bottom of an iron frame to be dropped by a wire into the sea. In the frame is an electro-magnet. The tube is held in a dark recess till the magnet is formed, and then it springs into the light, but is withdrawn again when the electric current ceases. The actinic force of the rays is, of course, determined from the amount of darkening produced on the paper in a given time.


Cheap Hydrogen Gas.—The statement comes from Paris that a Mr. Giffard has devised a process for the rapid production of hydrogen from water, which promises to make its use as an illuminator more economical than that of ordinary coal-gas. It is claimed that by this method hydrogen may be generated on a large scale, 18,000 cubic feet per hour, at a cost of from fifteen to thirty cents per thousand cubic feet, so that by combustion with solid refractory substances, such as magnesium, platinum, lime, marble, etc., it may advantageously compete with coal-gas for illuminating purposes.


Building-Stone and Fire.—Dr. Adolph Ott, in the Engineering and Mining Journal, treats of the resistance offered to fire by the various kinds of stone employed in building. According to this author, the presence of magnesia in limestone (magnesian limestone, dolomite) hastens the decomposition of the mass under the action of heat, the magnesia parting with its carbonic acid at the comparatively low temperature of 600 Fahr. Common limestone will stand a higher temperature without decomposition. As our Westchester and also Vermont marble is a magnesian limestone, this fact is of very considerable interest for this city. It appears that, in Chicago, as also probably in Boston, the sandstones made the most obstinate resistance to the heat. This is explained by the fact that the chief ingredient in stones of that class is quartz, a substance remarkable for its infusibility. As for granite, gneiss, mica-slate, and other rocks of the primary formation, which are commonly esteemed indestructible, Dr. Ott shows that they can make but very feeble resistance to heat. The water enclosed in such rocks accounts for their bursting and exploding when heated. Portland cement-stone is said to show extraordinary resistent power, almost equalling sandstone in this respect. Of brick walls the author is disposed to think well, provided they be honestly built of hard material throughout, and of the requisite degree of thickness.



Notwithstanding the high price of meat and the great scarcity of potatoes in England, there are this winter, says the Saturday Review, 40,000 less paupers in London than three years ago. This is owing to an organized system of transferring labor to portions of the country where it is most needed, and thus relieving the overstocked points where pauperism is always most rapidly developed. The Review calls for an extension of the system, and urges those who are wasting their funds in ill directed charities, which oftentimes actually increase the number of paupers, to give this one, which aims to make the lower classes self-sustaining, a fair amount of consideration.

Mr. T. C. Webb, of Philadelphia, has made experiments with a plate electrical machine, in an insulated room, that seem to show the fallacy of the ordinary theory of the discharge of a charged conductor. A room eight by nine feet, and about eight feet high, was constructed, and suspended upon gutta percha, and its perfect insulation shown by a Thomson galvanometer. The plate-machine acted in all respects the same as in an uninsulated room; sparks were given off, and the conductor completely discharged when touched to the sides of the building. The experiments given in the Philadelphia Magazine seem to show conclusively that the common theory of the electrical machine is erroneous.—American Manufacturer.