The age-herald., 1897-10-03
M@M 6R NR aQN NBl 8BQM M NQ QN & & @G S NOTES ON SCIENCE AND INDUSTRY. E

A method of preserving boilers nolt in use has been prescribed for the French navy. According to this the bollecs are completely filled with fresh waiter, and in the case of large boilers wiiln large tubes, thsre is added to the water a cer- tain amount of milk of lime or a sol1- tion of sdoa; in the case of tubular boil CTS with small tubes milk of lime or soda lis added, the solution, however, not be- ing so strong as for the larger tubes, in order to avoid any danger of contracting the effective area by deposit from the solution. The strength of the solution is to be just sufficient to neutralize any acidfty of the water. Care is enjoined to be taken to preserve ths outside of the steel or iron tubes in those boilers which are not to be used for long peri ods; such are for this purpose painted with red lead or coal tar as far as it is possible to reach, while for those DOT tions which are inaccessible a protective coating is obtained by burning under the tubes a certain amount of tar or coal tar, the smoke of these forming coating of soot, which prevents the air from reaching the surface of the tubes. Besides this treatment, the boiler cas- ing is closed and kept air-tigfrt after some quicklime has been placed inside. Periodical inspections of these boilers are made to insure the complete filling of the tubes.
 I. IS an interesting fact in the records or scientific progress that the United States navy has fer a. long time past been dropping bottles overheard in the Atlantic ocean at the Azores, in deep water along the coast of Spain, and from the Madeira and the Canaries south- ward along the coast of Africa. The fact that all these bottles that have been recovered have bsen found on the coast of South America, on the Antilles, and some of them as far west as the mouth of the Rio Grande, suggests the infer ence that every buoyant object which has been dropped into the ocean during the present geological epoch by prehis- toric or historic Spanards, Portuguese or Africans has found it's way to Ameri- ca and ben stranded somewhere be- tween the 01th parallel south of the 30th parallel north. In the northern part Of the Atlantic ocean the currents run the other way; and the mails have been delivered from America to Europe In the Pacific ocean the daily mails deliv- cred on the west coast of America from Mount St. Elias southward have pro ceeded from about the twentieth paral- Tel north, in the vicinity of the Malay peninsula and archipelago, thence have traveled through the China sea and the Japanese sea to pick up matters design ed for the western hemisphere.
 circular percussion table of peculiar mechanism Is in operation at the Ar gent mine, Tasmania, the machine con- sisting of cast-iron table thirteen feet in diameter convex in form turned smooth on the surface, and vibrated by cams worked by shaft underneath. The separation of the minerals from the gangue is by means of water currents supplied by a curved water pipe, revolv- ra6 S1nwlv Inc Of fa receptacles at the outer rim of the table receiving the several grades of concen- trates. The ore is fed onto the table with water and runs in a curved direc- tion toward the outer edge of the table. On its way the stream is reduced in ve- 1ocity and depth to about one-third, ow- ing to the greater surface covered, caus- ing a separation of the lighter and heavier particles; the former leave the table at once, while the latter are furth- CT separated by passing under the stream of Water from The ratating crrv- ed water pipe, which, assisted by the vibrations of the table, with gradually increasing energy and velocity, sepa- rates the various materials according to their specific gravity and washes them irto the rotating delivery recep- tacles. and thence into circular troughs, which collect the different sorts. The daily capacity of this machine is from twelve to fifteen tons
 Quite an ingenious device has been contrived by T. w. Haley, a well-known mechanician in Milford, Me, viz, a self lubricating bearing, which it is believed possesses superior qualities to anything yet proposed in this line. It consists of a compound of metal and graphite com- bined in such a manner as to hold the graphite in solution, this latter feature being lthe chief point of originality in the invention. All the metSls that are used fuse at much lower tempern ture than will vitrify glass, which requires 4000 degrees F. The metals employed are thoroughly mixed while in a pow dered form and combine before the glass becomes liquid, and are then pressed into the journal; this makes