ROTARY PRINTING MACHINE, 
399 
ON THE USE OF PIPE-CLAY IN 
WASHING. 
Sir, — I take this opportunity of observing, 
in respect to the use of pipe- clay in washing, 
as noticed in the extract from a Dundee pa- 
per, at p. 80 in your 665th Number, that the 
discovery is by no means a new one. 
The detergent properties of pipe-clay, ful- 
lers-earth, and other saponaceous clays, have 
been long known and taken advantage of 
both in domestic economy and in various 
manufacturing processes. In the army, and 
in the navy in particular, pipe-clay has been 
long and extensively employed in washing 
and whitening of wearing apparel and is 
well known to increase the effect, and reduce 
the quantity of soap and labour necessary to 
produce the effect required ; although the 
actual saving of both is somewhat overrated 
in the article quoted as above. 
There is no question but that a more ex- 
tensive diffusion of a correct knowledge of the 
real properties of these substances, which 
are in many places exceedingly abundant, 
will tend to produce increased economy in 
the application of two costly mateidals — soap 
and labour. 
1 remain, yours respectfully, 
W. Baddeley. 
Birmingham, June 27, 1836. 
ELECTRIC CURRENTS. 
At a late meeting of the Royal Society a 
paper was read “ On the reciprocal attrac- 
tions of positive and negative Electric Cur- 
rents whereby the motion of each is alter- 
nately accelerated and retarded,” by P. Cun- 
ningham, Esq. Surgeon, R. N., communi- 
cated by Alexander Copland Hutchison, Esq. 
The following abstract of which we quote 
from the Athenmum . — 
“ The author found that a square plate 
of copper, six inches in diameter, placed ver- 
tically in the plane of the magnetic meri- 
dian, and connected with a voltaic battery by 
means of wires soldered to the middle of two 
opposite sides of the plate, exhibited magne- 
tic polarities on its two surfaces, indicative of 
the passage of transverse and spiral electrical 
currents, at right angles to the straight lines 
joining the ends of the wires. The polari- 
ties were of opposite kinds on each side of 
this middle line, in each surface ; and were 
reversed on the other surface of the plate. 
The intensities of these polarities at every 
point of the surface were greatest the greater 
its distance from the middle line, where the 
plate exhibited no magnetic action. The au- 
thor infers from this and other experiments 
of a similar kind, that each electric current is 
subject, during its transverse motion, to al- 
terations of acceleration and retardation, the 
positive current on one side of the plate, and 
the negative on the other, by their reciprocal 
attractions, progressively accelerating each 
other’s motions, as they approach, in oppo- 
site directions, the edge round which they 
have to turn. After turning round the edge 
their motion will, he conceives, be checked, 
by coming in contact with the accelerated 
portions of the opposing currents to which 
they respectively owed their former increase 
of velocity ; so that the one current will be 
retarded at the part of the plate where the 
other is accelerated. To these alternate 
accelerations and retardations of electric 
currents during their progressive motion, the 
author is disposed to refer the alternate dark 
and luminous divisions in a platina wire heat- 
ed by electricity, as was observed by Dr. 
Barker.” 
PATENT ROTARY PRINTING-APPA- 
RATUS. 
A patent has recently been taken out by 
Mr. Rowland Hill for a rotary printing- 
machine. The types are imposed* upon cy- 
linders, to which they are firmly attached, and 
of which, except the marginal spaces, they 
occupy the whole surface. The pressure is 
given by blanket-covered cylinders of the or- 
dinary construction. 
The most important advantages of this ar- 
rangment are stated to be, first, That as the 
revolving type cylinder is constantly receiving 
its ink in one part of its revolution, and con- 
stantly impressing the paper in another part, 
the action of the machineis unceasing; where- 
by a saving of time of about three parts out 
of four is obtained in comparison with the 
ordinary printing machines, when moving at 
the same velocity ; because in those machines 
the backward motion of the form,* and the 
laying on of the ink, suspend for the time the 
process of printing. Further, as the motion 
of the type in this machine is continuous 
instead of reciprocating, the speed has been 
increased without difficulty or danger ; and 
by this additional velocity, combined with 
the saving of time just described, the rate of 
printing is brought to about ten times that 
of the ordinary perfecting machines, i. e. 
those vffiich print the sheet on both sides be- 
foi*e it leaves the machine. Secondly, the 
reciprocating motion of the heavy form, ink- 
ing table, and inking rollers of the ordinary 
machine entails such a loss of power and time, 
in comparison of the rotatory motion which 
is here substituted for it, that it is believed, 
from careful observation, that, notwithstand- 
ing the great increase in speed, any given 
quantity of work will be executed at the 
expense of about one-eighth of the power 
required in the ordinary machine. 
The facilities provided for fixing the type, 
detaching parts for correction, apppiying the 
ink, and regulating its supply, are said to be 
fully equal, if not superior, to those of other 
machines. 
Compared with the rapid machines used for 
printing the daily newspapers, the rotatory 
machine will print two sheets on both sides 
with accurate register*, while they print one 
sheet on one side with defective register. 
• These words are used technically. 
