52 Scientific Intelligence. 
set itself across the a of chat steady current of the fluid in 
which it is immersed, anc may fairly suppose that an effect of 
the same character will follow from an alternating current. At 
the moment of the tap upon the box the air Einside 5 is vmade to move 
is as if an impulse had been given to the suspended par 
he experiment shown is intended to illustrate this offot. A 
avoid any possible disturbance due to the were om a of the 
vibrating prongs s.— Cambridge Phil. Soc., Nov. 8 
4. Edison’s Electrical Meters.—A recent pai le (Nov. 23), of 
the excellent electrical Journal “La Lumiére Electrique,” con- 
tains a stain tae by the scientific editor, M. Th. Du Moncel, of 
two forms of meters designed by Mr. Edison to measure the’ 
amount of electricity consumed in a given case either for mechan- 
ical purposes or for lighting. One of these is very simple in con- 
struction, but requires that a weighing operation should be per- 
formed each time it is ar to learn the amount of electricity 
which has been consu ; the other is somewhat more compli- 
cated, but icaimpaael: all its Hoary seg — a 
record on a dial after the manner of ordinar gas 
The first of these consists of two closed copper batphate volta- 
ware placed in separate adjoining compartments of the enclos- 
ing case; to one of these subscriber is supposed to have 
aie and the other is to be used for verification by the officer of 
the company which supplies the electricity. The electrodes in 
each cell are formed of copper plates placed near to each other so 
that as the current passes a deposit of copper is made on one of 
them by the isa branch action. The curr feng passing through 
the ecb is a h of the main current which is being 
used, and b sof a small resistance coil its intensity is re- 
du ne toa er faster, perhaps one ee of it. The 
oo of the instrument is as follows: the one passes in 
naiaiea, a certain bows ‘portion of it pearmnee the two volta- 
meters and causes in them a deposit of eg which is propor- 
tional to the given current in the given time. As the exact. rela- 
tion between the intensity of the current whieli traverses the vol- 
tameters to the main current is known, it is easy to deduce the 
quantity of electricity which has been used from the amount of 
copper deposited on the negative electrode; the weight of copper 
