THE YOUNG SCIENTIST. 
maelstrom off the coast of Norway, attaching: to 
it cables which shall span the oceans, and 
which, when the wheel once starts in motion, 
as it is, of course, sure to do in this wonderful 
current, will furnish power for everyl)ody. All 
the expenses attached to this will be rep;i,irs to 
the wheel and the cables which may occur from 
time to time, ' And,' said the inventor to a re- 
porter, ' you know that will amount to almost 
nothing.' " 

Photographs that Wink. 
The last new thing in photography surpasses 
the ingenuity of the man who invented the 
rspirit pliotographs, and suggests how handy it 
would have been had that crafty person added 
■this to liis devices. A Frenchman takes one 
jiegative of a sitter with open eyes. Then he 
.makes the sitter shut his eyes and remain in 
/exactly the same position while another nega- 
;tive is taken. The two negatives are printed 
on the same paper, one on each side exactly 
coinciding. When this double-faced picture is 
held in proper position before a lamp, and the 
J lamp is rapidly moved or caused to flicker, the 
curious effect is produced of long-continued 
.winking. It is not claimed that a person looks 
more beautiful when he keeps winking, but it 
cannot be denied that it gives one a very inter- 
>esting appearance. 
plant now has leaves six feet in diameter, and 
lifis unfolded its first flower, wliieh was the ad- 
miration of all beliolders. Mr. Sturtevant's plant 
will continue to bloom for several weeks. 
Rendering" Tissues Waterproof.— Prepare 
the two following solutions: 2 lb. 8 oz. parafflne 
dissolved in 10 lb. tar-benzine, and 8 oz. caout- 
chouc dissolved in 5 lb. tar-benzine. The two 
solutions are well mixed together before using, 
Mild 8 oz. linseed oil varnish is added to the 
mixture. This mixture is spread cold on the 
tissue by means of a brush once on each side of 
the cloth. 
Preservation of the Colors of Dried 
Plants.— According to M. Storbzl, the slow im- 
mersion of the fresh plant in a boiling solution 
of«one part of salicylic acid in 600 parts of alcohol, 
..nd then shaking off superfluous moisture, previ- 
ous to pressing in the usual way between blotting- 
pai^er, will more nearly preserve the natural color 
than any other method. 
Metrical Abbreviations.— The following 
abbieviatioiis for metrical units have recently 
been decreed by the Spanish Government for 
Spain and its colonies: 
Reversing the Wheels. 
^Experiments lately made at Blackburn with a 
train made up in imitation of that of the express 
which ran into the train standing in Blackburn 
station, to test the statement of the driver that 
he reversed his engine as soon as he found the 
^brakes did not check his train, are of some in- 
terest, though they elicited the fact that the 
reversal of the engine of a train running at a 
high velocity has but a very small effect in re- 
ducing the speed. A high speed was attained, 
and the engine was reversed a quarter of a mile 
before reaching the station, but the train ran 
through the station at about 20 miles an hour, 
and had to be stopped by the brakes. Loco- 
motive driving wheels, when running the re- 
verse way, are not effective in stopping a train. 
The experiment shows hew little can be gained 
by reversing an engine under such circum- 
stances. 
Practical ^ints. 
The Victoria Regia.— Mr. E. D. Sturtevant, a 
florist of Bordentown, N. J., has accomplished a 
feat hitherto unknown in the annals of floricul- 
ture in this country, that of growing to perfection 
in the open air a plant of the famous victoria 
regia, the giant water lily of South America. The 
Cubic decimeter dm3. 
Cubic centimeter cms. 
Cubic millimeter mmS. 
Hectoliter hi. 
Decaliter dal. 
Liter. 1. 
Deciliter dl. 
Centiliter cl. 
Ton t. 
Metrical cwt q. 
Kilogram kg. 
Gramme g. 
Decigramme dg. 
Centigramme eg. 
Milligramme mg. 
Kilometer. km. 
Meter m. 
Decimeter dm. 
Centimeter cm. 
Millimeter . - .mm. 
i-icoo millimeter, or 
micro-millimeter... mmm. 
Square kilometer km2. 
Hectare ha. 
Are a. 
Square meter in2. 
Square decimeter dm2. 
Square centimeter cm2. 
Square millimeter mm2. 
5 Stere S. 
^ Cubic meter ms. 
Silvering" Iron.— A manufacturer in Vienna 
employs the following process for silvering iron: 
He first covers the iron with mercury, and silvers 
by the galvanic process. By heating to 300° C, 
the mercury evaporates and the silver layer is 
fixed. Ironware is flrst heated with diluted 
hydrochloric acid, and then dipped in a solution 
of. nitrate of mercury, being, at the same time, in 
communication with the zinc pole of an electric 
battery., a piece of gas carbon or platinum being 
used as an anode for the other pole. The metal 
is soon covered with a layer of quicksilver; is 
then taken out and well washed and silvered in a 
silver solution. To save silver the ware can be 
flrst covered with a thin layer of tin ; one part of 
cream of tartar is dissolved in eight parts of 
boiling water, and one or more tin anodes are 
joined with the carbon pole of a Bunsen element. 
The zinc pole communicates with a well-cleaned 
piece of copper, and the battery is made to act 
till enough tin has deposited on the copper, when 
this is taken out and the ironware put in its 
place. The ware thus covered with tin. chemic- 
ally pure and silvered, is much cheaper than any 
other silvered metals. 
