[ 546 
{Jan. 1, 
VARIETIES, LITERARY AND MISCELLANEOUS; 
Including Notices of Works in Hand, Domestic and Foreign. ~ 
— 
Wwe have seen many attempts to 
explain. theypyipeiples of Mr. 
Perkins’s new steam-engine, but none 
whichis; more likely to render them 
plain. to every capacity than the 
observations contained in the | Four 
Dialogues, just published between an 
Oxfurd Tutor anda: Disciple of the 
Common Sense Philosophy. Many of 
our readers will therefore thank us 
for giving place to the passage :— 
. “The basis of Mr. Perkins’s improvement 
consists in his bringing water into actual 
contact with the metal, by which the ex- 
citement is directly communicated to the 
water, which excitement, heretofore, has 
been allowed to dissipate itself by the 
simultaneous generation of steam. _ The 
atomic motion, transferred by the fixation 
of the gases in the process of the external 
combustion, passes through the substance 
of the vessel .containing the water, and its 
first effect has been to convert the ad- 
joining liquid into steam. Room being al- 
lowed in ordinary boilers for the expansion 
of this steam, the ultimate force consisted 
only of the first simple force; or, if accele- 
rated, the acceleration depended on the 
vague dimensions and decreasing strength 
of an extended surface of boiler. But Mr. 
Perkins has contrived to press his liquid 
into his boiler, or generator, home to the in- 
terior surface of his generator, and to keep 
it full, so that no steam can be simulta- 
neously generated; and hence, as the motion 
transferred by the fixation of the gases in the 
adjacent combustion is not simultaneously 
distributed in steam, the contained water 
receives all the acceleration of excitement 
of which it is susceptible. This accumulated 
excitement does not, however, burst the ge- 
nerator, because the strength, other things 
alike, is inversely as the dimensions, and 
the thickness can, conveniently, in so small 
a bulk, be, istereased to any required de- 
gree; thus, less of the motion, transferred 
from the combustion is lost, than when, by 
the old system, steam was simultaneously 
generated ; and the continued addition 
accelerates the excitement of the water, 
on the principle of accelerated motion in 
falling bodies: From this effect, of ac- 
eeleration; which cannot 'be complete in an 
* ordinary expanded boiler, Mr. Perkins 
obtains great. excitement with much, less 
fuel, orless gas-fixing, by.combustion. .He 
loses no motion, and he appropriates,the 
whole by an accelerated result. The ex- 
pansive force is all the motion of the gases 
fixed by the combustion ; and, as long as 
the stréngtli of cohesion in the materials of 
the generator is greater than the expansive 
force, no explosion can take place. But, as 
soon as Mr. P. has sufficiently excited his 
water, he allows some of it fo escape, and 
every drop then evolves in steam many 
hundred times the original bulk, The 
excited atoms, of course, perform large 
orbits, creating a local yacuum, therefore, a 
perception of coldness to the evaporating 
hand plunged into it, and a force of ex- 
pansion equal to any required, as 500\bs. 
or 20,000lbs. to the squate inch. Itisa 
case of motion compressed. The confined 
atoms of water are not to be supposed at 
rest; on the contrary, no motion is lost or 
gained in the whole process. It previ- 
ously existed in the gases of the atmosphere; 
these are fixed by the combustion, which 
is a mere process of gaseous fixation; the 
generator and its contained water are 
placed in contact; the,atoms in water re- 
ceive the motion, but are unable, for want 
of space, to exliibit any of it in forming 
steam; the contintiance of the transfer of 
motion causes acceleration, and a violent 
tendency tg escape, which, however, is 
prevented, till the excitement is sufficient 
to evolve gas of the required power.» Ra- 
tionally explained, Mr. P.’s machine is 
founded on principlesstrictly philosophical: 
—he has safely generated a force before 
unknown; and, if he had failed to apply it 
with skill, his past reputation, as a me- 
chanic of the first order, would have been 
undeserved. Till we have fallen upon .a me- 
thod of applying guses themselves in various 
degrees of condensation, as contrasted me- 
chanical powers, we must be content to re- 
gard Mr. Perkins’s contrivance for pro- 
ducing the same power with one gallon of 
water as with sixty, and with one bushel 
of coals as with four, as the limit of human 
ingenuity in this branch of human’ art. At 
the same time I am persuaded, that the ap- 
plication of the force transferred by, com- 
bustion through water, for the purpose of 
arriving at mechanical. power, will by 
posterity be considered as a very bungling 
procedure; and I think that it has been 
continued merely because mankind have 
been confounded by ‘the nonsense about 
caloric; and, in consequence, have not un- 
derstood the nature and source of the 
power which they were applying.” 
Volume the Second is announced of 
Travels in the Interior of Southern 
Africa, by W. J. Burcuect, esq. with 
a large and entirely-new map, and 116 
coloured and black engravings. 'The 
author penetrated into the heart of the 
Continent, to the depth of nearly 1100 
miles; and, besides the complete nar- 
rative of daily occurrences, as far as 
the most distant town in the Interior, 
and of the various transactions with 
the natives, this work contains a gene- 
ral account of the inhabitants, and in- 
teresting 
