120 
SCIENCE. 
cause corresponding variations in the heat at the point of 
contact of the needle with the cylinder, and this again pro- 
duces a mechanical movement of the pressing point, as 
well as of the air surrounding it, sufficient to give forth 
sound-waves. If such be the case the effect should be dif- 
ferent for different metals, those answering best which have 
the lowest thermal conductivity and also the lowest specific 
heat. That this is really so, is showing by substituting 
cylinders of other metals for the bismuth, all other things 
remaining the same. In this way I have compared lead, 
tin, iron, copper, carbon, and find that they all give forth 
the simple loose contact sound when the cylinder is station- 
ary, but that it is only with bismuth that there is any very 
great intensification of the sound when the cylinder is 
rotated. Now, by consulting the appropriate tables I find 
that bismuth is a fraction lower than any other common 
metal in specific, while heat is much below them all, in 
thermal conductivity. This seems to bear out my explana- 
tion to a certain extent. 
The subject of a depraved taste in animals is an interest- 
ing one, which has not been studied as much perhaps as it 
might. In human beings it would seem to depend on ill- 
health of either body or mind, but in animals it would seem 
as if it might be present and the animal enjoy good health. 
One remarkable instance in an herbivorous animal we can 
vouch for. It occurred in a sheep that had been shipped on 
board one of the P. and O. steamers to help to supply the 
kitchen on board, but while fattening it developed an inor- 
dinate taste for tobacco, which it would eat in any quan- 
tity that was given to it. It did not much care for cigars, 
and altogether objected to burnt ends ; but it would greed- 
ily devour the half-chewed quid of a sailor or a handful of 
roll tobacco. While chewing there was apparently no un- 
due flow of saliva, and its taste was so peculiar that most 
of the passengers on board amused themselves by feeding 
it, to see for themselves if it were really so. As a conse- 
quence, though in fair condition, the cook was afraid to 
kill the sheep, believing that the mutton would have the 
flavor of tobacco. Another very remarkable case has just 
been communicated to us by Mr. Francis Goodlake: this 
time a flesh-eating animal in the shape of a kitten, about 
five months old, who shows a passionate fondness for sal- 
ads. It eats no end of sliced cucumber dressed with vin- 
egar, even when hot with cayenne pepper. After a little 
fencing it has eaten a piece of boiled beef with mustard. 
Its mother was at least once seen to eat a slice of cucumber 
which had salt, pepper and vinegar on it. The kitten is 
apparently in good health, and its extraordinary taste is not 
easily accounted for. Even supposing it once got a feed 
of salmon mayonaise, why should it now select to prefer 
the dressing to the fish ? — Nature. 
Natural Enemies of the Telegraph. — There is, appa- 
rently, no apparatus so liable to be interfered with by what 
we may call natural causes as the electric telegraph. Fish 
gnaw and mollusks overweight the submarine conductors 
of the subterranean wires ; while there is at least one in- 
stance of a frolicsome whale entangling himself in a deep 
sea cable, to its utter disorganization. It is stated that 
within the three years ending 1878, there have been sixty 
serious interruptions to telegraphic communication in 
Summatra, by elephants. In one instance, these sagacious 
animals, most likely fearing snares, destroyed a consider- 
able portion of the line, hiding away the wires and insula- 
tors in a canebreak. Monkeys of all tribes and sizes, too, 
in that favored island, use the poles and wires as gymnasia, 
occasionally breaking them and carrying off the insulators ; 
while the numerous tigers, bears and buffaloes on the track 
render the watching and repair of the line a duty of great 
danger. In Australia, where there are no wild animals to 
injure the wires, which are carried great distances over- 
land, they are said to be frequently cut down by the scarcely 
less wild aborigines, who manufacture from them rings, 
armlets and other varieties of barbaric ornament It has 
been suggested as a means of protection in this case that 
the posts should be const! ucted of iron, when the battery 
could be used to astonish any native climbing them with 
felonious intent . — Scientific American , 
PHYSICAL NOTES. 
In an article of great length, extending through the last 
three numbers of the Annalen der Physik und Chemie, which 
exhibits extraordinary scope of research and ingenuity, the 
learned Professor Quincke exhausts the subject of elec- 
trical expansion. The following results are drawn from 
his investigation : 
1. Solid and liquid bodies alter their volume when they 
are acted upon, the same as Leyden jars, by electrical 
forces. 
2. This change of volume is not the effect of heat, but is 
mostly an expansion ; though it may also be a contraction, 
as in the case of the fatty oils. 
3. No change of volume was observable in gases under 
the action of electrical forces. If such occurred it was 
smaller than aoutnAruSuo of the original volume. 
4. There was an instantaneous change of volume in flint 
glass, but it took longer in German glass, which is a better 
conductor of electricity. By discharge of the coatings of 
spherical and tubular condensers, the glass resumes its 
original volume. 
5. There is a simultaneous change of length and volume 
in tubular condensers. 
6 . The change of volume and length increases as the 
difference of potential in the coatings, and inversely as the 
thickness of the insulating substance of the condenser ; 
and they are nearly proportional to the square of strength 
of potential and thickness. 
7. Under otherwise equal conditions the expansion in 
volume and length differ according to the insulating sub- 
stance of the condenser. 
8. After the discharge of the coatings of the condensers, 
there is a residue, so to speak, of this change of volume, 
which is very small in the case of flint glass, but greater in 
German glass, and which seems to have some connection 
with the electrical polarization of the mass of the glass 
itself. 
g. The change of mass and volume does not result from 
an electrical compression of the insulating substance. 
to. In flint glass electrical expansion takes place equally 
in all directions, as in the expansions produced by increase 
of temperature, independent of the character and direction 
of the electrical forces. 
11. Electrical change of length and volume takes place 
in glass nearly in the same way with increase of tempera- 
ture, as the dialectric constants, or the electrical conduc- 
tivity of the glass. 
12. Action of electrical forces diminish the elasticity of 
flint glass, German glass, and caoutchouc, but increase 
that of mica and gutta percha. 
13. The electrical piercing of glass and other substances 
is a result of the unequal electrical expansion of the insula- 
tor in different places. 
14. By unequal electrical expansion solid and liquid 
substances are unequally dilated and become double re- 
fracting, as other similar substances do when heated. 
15. Glass, when equally expanded, shows no electrical 
double refraction under electrical forces. 
16. The relation of substances with positive and negative 
double refraction (to which Dr. Kerr first called attention), 
is explained by the way in which different substances change 
their exponents of refraction with their density and volume. 
17. With a constant difference of potential in the coating 
of a condenser, after long charging, the electrical force 
varies in different layers of the insulative substance at the 
same time, or in the same place at different times. 
M. Berthelot has recently made an apparatus for 
measuring the heat of combustion of gases by detonation, 
which consists essentially of a bomb suspended in a calori- 
meter. 
Mr. W. E. Hidden, the mineral collector, has discovered 
in Burke County, N. C., a new locality of Furgusonite. 
The mineral was chemically determined by Dr. J. Lawrence 
Smith. 
