1808.] 
figures attached to it very numerous; an 
abridgment of the former would be of 
ho use unless we had the opportunity 
of presenting our readers, at the same 
time, with the copies of the latter; we 
shall therefore give the principle only on 
which the method is grounded, | 
It is known that when a cylinder rolis 
on a plane, every point in the circum- 
ference of that cylinder describes a curve 
called a cycloid ; and,. that if a cone 
turns on its axis, while the latter gyrates 
round a given centre coinciding with the 
summit of the cone, then every point in 
the circumference of the cone will de- 
scribe a spherieal cycloid; and, if a cy- 
linder of a smaller diameter revolves 
round its axis, and rolls within a hollow 
éylinder of a larger diameter, then every 
point of the smaller cylinder will describe 
an epicycloid within the larger cylinder. 
This is the chief principle of the inven- 
tion. ‘The surfaces of the contiguous 
- bodies are to be furnished with a great 
number of books or eard-wires, adapted 
“Literary and Phitosophicaé Intelligence. 
527 
to this kind of motion; and every time 
they meet, if there is wool between them, 
the hooks of both surfaces will seize 
each one half of the whole, and divide it 
each tine that such contact takes place, 
so that after a certain number of turns 
the wool will be fully opened and pre- 
pared for the further operations pre- 
paratory to spinning, To this it 1s add- 
ed; that if while a smalter cylinder: 
rol!s on a plane, and a larger fixed to it 
be considered with respect to ifs surface, 
any point in the latter surface will de- 
scribe a curve of the nature of the cycloid, 
but forming a loop so as to move back- 
ward for amoment, while the common 
centre of the two cylinders 1s moving for- 
ward, Thus a new system of opening 
or carding filamentous substances is 
founded on the general principle of cy- 
cloidal and epicycloidal motions, so mo- 
dified as to rub to any degree by the re 
lative diameter of the gyrating cylinder 
compared with that of the wheel which 
gives 1t motion, 
Wee 
* 
VARIETIES, LITERARY nS PHILOSOPHICAL, 
. Including Notices of Works in Hand, Domefiic and Foreign. 
* * Authentic Communications forthis Article will always be thankfully received, 
ER : * 
N R. DAVY, in the concluding Lec- 
Ee tures of his Course at the Royal 
Institution, gave a distinct and very lu- 
miinous exhibition of his grand discovery, 
the decomposition of the alkalies. His 
first experiments were with potash and 
- soda, which, im their dry state, are non- 
conductors, -but’ when moistened, have 
the property of conducting electri- 
eity. In both instances he clearly pros 
duced metalline substances, by bringing: 
them within the action of the Voltaic 
battery. Oxygen was given out at the 
positive side of the battery, and at the 
negative little globules of ihe metallic 
base were instantly formed. The me-. 
talline bases of the alkalies, he named 
potassium and sudaium, chusing the 
termination wm, in compliance with the 
present nomenclature of metals, in order 
that they might agree with” platinum, 
plumbum, &c. &c. These new metals, 
to appearance, are precisely like mercury, 
but very different from that metal in their 
various properties, which he enumerated 
and demonstrated to the satisfaction of 
every ofe present. Heshowed the great 
inflammahuility ofthe new metals,by touch- 
ing them with the smallest quantity of 
Montury Mae, No. 172. 
water, when they instantly took frre, 
They are both malleable at the common 
temperature, and may be spread into 
very thin leaves on a plate of glass, by 
mere pressure, So great, however, is 
their attraction for the oxygen of the at- 
mosphere, that they almost instantly bes 
came tarnished. Before the discovery 
of these new metals, only two bodies of 
this class, viz. iron and platinum, were ca- 
pable of being welded, and that at a very 
great heat, whereas separate parts of the 
potassium and sodaium, can be united 
readily at the common temjerature of 
the atmosphere. The specific gravity of 
the potassium, is to that of water as 
about six to ten; in the case of sodaium 
it is as ninety-three to one hundred, Mr. 
Davy showed, that the metals which he 
had spread on glass, were easily fusible 
again by the heat ofa spiritlamp, by the 
application of which they almost instantly 
ran into glabules. The attraction of 
these new inetals for oxygen, was shewn 
by their burning at a red heat, when the 
alkalies were again revived. * In analyze 
ing them with great accuracy, he found 
the’ potash contained fourteen parts of 
oxygen, and cighty-four of metalline base. 
4 ah Dug 
