1825.] 
[ 343 J 
SPIRIT OF PHILOSOPHICAL DISCOVERY, AND OF THE 
VARIOUS SCIENTIFIC JOURNALS. 
—<>—. 
HE Prangos Hay Plant, of Northern 
India, appears to be remarkable for 
its amazing produce, and its beneficial 
effects when used as a food for cattle, while 
very little care is requisite in its cultivation. 
Two chests of its seed, and specimens 
of the Prangos Hay, have been forwarded 
to this country, and presented by the Hon. 
Court of Directors of the East-India Com- 
pany to the Horticultural Society; and 
though it is much to be regretted, that the 
vegetative power of the seeds had been so 
much exhausted, as to render it doubtful 
whether they will grow or not, there is 
reason to hope, that speedier means may 
be employed to obtain seed, now, that 
attention is called to the plant. The Pran- 
gos Hay Plant is a perennial herbaceous 
plant, with a large fleshy root-stock, usually 
measuring six or seven inches in diameter ; 
and formed by the aggregation of an im- 
Mmense quantity of crowns, or winter buds, 
clustered together at, or above the surface 
of the ground. These crowns are closely 
covered by the fibrous remains of the old 
leaves, which must be effective in protect- 
ing the buds from frost. From each crown 
rises an abundance of finely cut leaves, 
about two feet in length; and of a highly 
fragrant smell when dried, similar to that 
of new clover hay. Mr. Lindley (judging 
from the specimen) supposes, that each 
plant will produce about 14 lbs. of dry 
fodder; and, allowing each plant to occupy 
a space of ground four feet square, the pro- 
duce would be 13 tons per acre ; and it is 
said to thrive on very inferior land. —Quar- 
terly Journal of Science, No. 39, p. 1. 
The following deductions respecting the 
Temperature of the Earth’s Surface have 
been made by the Editor of the dnn. de 
Chimie, from a general and extensive review 
of the various observations that have been 
made on this subject. Ist: In no place, 
on the earth’s surface, nor at any season, 
will a thermometer, raised from six to nine 
feet above the soil, and sheltered from re- 
flected heat, attain the 115th degree of Fah- 
renheit.—2d, on the open sea, the tem- 
perature of the air, whatever be the place, 
or season, will never attain 88 degrees of 
Fahrenheit.—3d. The greatest degree of 
cold ever observed on our globe, with a 
thermometer suspended in the air, is 58 de- 
grees below Zero of Fahrenheit.—4th. ‘The 
temperature of the water of the ocean, in 
any latitude, or at any season, never rises 
-above 86 degrees of Fahrenheit. 
It has been ascertained, that the Copper 
Rings with which Dipping Needles are gene- 
rally surrounded, have a singular effect on 
the magnetic needle ; in the copper rings, 
the amplitude of the oscillations rapidly 
diminish, but their duration is not sensibly 
altered.. In M. Arago’s experiments, 
when a horizontal needle, suspended in a 
ring of wood by a thread, without tension, 
was moved 45° from its natural position, 
and left to itself, it made 145 oscillations 
before the amplitude was reduced to 10°. 
In a ring of copper, the amplitude reduced 
from 45° to 10° in 33 oscillations. In a 
lighter copper ring, the amplitude reduced 
from 45° to 10° in 66 oscillations. The 
time of the oscillations appeared to be the 
same in all the rings. 
The Intensity of the Electro-dynamic 
Force has been ascertained, by M. Beque- 
rel’s experiments, to be constant for all 
points of a metallic wire, joining the two 
poles of a voltaic pile. : 
The temperature, corresponding to the 
Maximum Density of Water, is 39,394° Fah- 
renheit, according to Professor Hillostrém’s 
experiments, in which every cause which 
interfered with the results was estimated, 
in such a manner as, in the professor’s opi- 
nion, to limit the uncertainty of error on 
either side to less than half a degree. 
The Drawing of Iron and Steel Wire is 
found to be much facilitated by the use of 
a weak solution of copper in the acid liquor 
employed for pickling the wire. The thin 
coat of copper, which precipitates upon the 
iron or steel, makes it easier to draw 
through the plates, andit requires to be 
annealed less frequently. The thin coat of 
copper is entirely removed by the last an- 
nealing process.— Tech. Rep. 
A process for ascertaining the Power of 
Building Materials to resist Frost, has lately 
occupied a considerable share of the atten- 
tion of the French philosophers. It con- 
sists In causing a fragment of the material, 
by boiling, to absorb a saturated solution 
of Glauber’s salt, the spontaneous crystal- 
lization of which disintegrates the stone, in 
the same manner as the freezing of water 
in its pores. If the stone be boiled too 
long, in the solution, or the saturation be 
effected at too high a temperature, the force 
of crystallization exceeds the usual effects 
of frost ; therefore, to avoid error in this 
respect, a series of instructions are given, 
for conducting the process. Water is to be 
saturated with Glauber’s salt at the com- 
mon temperature ; the solution is to be 
boiled; and while boiling freely, the speci- 
mens are to be introduced, and the boiling 
continued for half an hour and not. longer. 
The specimens are then to be withdrawn, 
and suspended by threads, with a small 
vessel, containing some of the solution, 
under each specimen. In about 24 hours, 
but depending on the state of the atmos- 
phere, the specimens will be found covered 
with small white crystals ; they are then to 
be 
