32 A New Mineral from the Azores. 
magnet, so that, at least, the smaller induced currents may not 
be felt by the machine. It must be recollected, that the inductive 
influence takes place at a distance through all bodies, conductors 
and non-conductors ; and hence no coating that can be put upon 
the wire will prevent the formation of induced currents. 
I think it not improbable, since the earth has been made to act 
the part of the return conductor, that some means will be di 
covered for insulating the single wire beneath the surface of the 
earth ; the difiiculty in effecting this is by no means as great as 
that of insulating two wires, and preventing the current striking 
across from one to the other. A wire, buried in the earth, would 
pr , In most cases, from the effect of a direct discharge ; 
_ but the inductive influence would still be exerted, though per- 
haps in a less degree. 
he wires of the telegraph are too small and too few in num- 
ber to affect, as some have supposed, the electrical condition of 
the atmosphere, by equalizing the quantity of the fluid in differ- 
ent places, and thus producing a less changeable state of the 
weather. ‘The feeble currents of electricity which must be con- 
stantly passing along the wires of a long line, may, however, with 
proper study, be the means of discovering many interesting facts 
relative to the electrical state of the air over different regions. 
Arr. Ifl—A New Mineral from the Azores ; by J. EB. Trscur- 
MACHER. 
Iy examining a portion of a volcanic boulder from St. Michael’s, 
Azores, for specimens of Pyrrhite, I discovered several small 
crystals, apparently octahedrons, of a translucent slightly yellowish 
white color, which alone before the blowpipe were totally infusi- 
e; on farther examination they proved to be nearly pure colum- 
bate of lime. The following is a description of them. 
Form—a square prism terminated by four-sided pyramids. 
M one = 133-40 
seapage “ ¢ == 123-15 ¢ by the reflecting goniometer. 
DZ M“M = 90 
Nearly all the crystals are in the form of obtuse octahedrons, the 
vertical axis being shorter than the lateral; one or two were 
found with prisms about the height of the pyramids—these were 
measured.* 
The color is usually translucent to opake white, with a very 
faint greenish yellow tinge; one or two were however as clear as 
fine quartz ; these were probably pure columbate of lime. 
” Specimens of this mineral, received through the kindness of Mr. Teschemacher, 
correspond entirely to the description above given.—J. D. D. 
