How the Kind of White Metal is Made That is Used in the Manufacture of Cheap Table Ware.—­How same can be hardened and still retain its color?  The following are formulas for white metal.  Melt together:  (a) Tin 82, lead 18, antimony 5, zinc 1, copper 4 parts. (b) Brass 32, lead 2, tin 2, zinc 1 part.  For a hard metal, not so white, melt together bismuth 6 parts, zinc 3 parts, lead 13 parts.  Or use type metal—­lead 3 to 7 parts, antimony 1 part.

What Metal Expands Most, for the Same Change in Temperature?—­For one degree Centigrade the following are coefficients of linear expansion:  aluminum, 0.0000222; silver, 0.0000191 to 0.0000212; nickel, 0.0000128; copper, 0.0000167 to 0.0000178; zinc, 0.0000220 to 0.0000292; brass, 0.0000178 to 0.0000193; platinum, 0.0000088.

Heavy Timbers.—­There are sixteen species of trees in America, whose perfectly dry wood will sink in water.  The heaviest of these is the black iron wood (confalia feriea) of Southern Florida, which is more than 30 per cent. heavier than water.  Of the others, the best known are lignum vitae (gualacum sanctum) and mangrove (chizphora mangle).  Another is a small oak (quercus gsisea) found in the mountains of Texas, Southern New Mexico and Arizona, and westward to the Colorado desert, at an elevation of 5,000 to 10,000 feet.  All the species in which the wood is heavier than water belong to semi-tropical Florida or the arid interior Pacific region.

Highest Point Reached by Man was by balloon 27,000 feet.  Travelers have rarely exceeded 20,000 feet, at which point the air from its rarity is very debilitating.

Has a Rate of Speed Equal to Ninety Miles an Hour, ever Been Attained by Railroad Locomotive?—­It is extremely doubtful if any locomotive ever made so high a speed.  A mile in 48 seconds is the shortest time we have heard of.  A rate of 70 to 75 miles per hour has been made on a spurt, on good straight track.  The Grant Locomotive Works could make such an engine.  Sixty miles an hour for a train is considered a very high rate of speed, and is seldom attained in practice for more than a short run.

The Fastest Boat in the World.—­Messrs. Thornycroft & Co., of Chiswick, in making preliminary trials of a torpedo boat built by them for the Spanish navy, have obtained a speed which is worthy of special record.  The boat is twin-screw, and the principal dimensions are:  Length 147 ft. 6 in., beam 14 ft. 6 in., by 4 ft. 9 in. draught.  On a trial at Lower Hope, on April 27, the remarkable mean speed of 26.11 knots was attained, being equal to a speed of 30.06 miles an hour, which is the highest speed yet attained by any vessel afloat.