THE BUBAL HEW-¥©BMEB. 
itimtifit atttr Useful. 
SOMETHING ABOUT GTEAM-POWLR. NO. 3. 
Tnc medium by which the energy inherent in 
compressed steam ia brought into useful action, . * 
is tho steam engiuo—tho most valuable gift ! ' 
Science has ever made to Industry. Tho names i 
and varieties of engines ai'fl multitudinous, yet 1 
they may all be conveniently classified under 1 
two heads—condensing and non-condensing eu- ■ 
gines. In this country llio former are almost 
invariably, though not necessarily, low and the 
latter hlgh-pressuro engines. Low-pressure en¬ 
gines are worked with steam having a pressure 
of loss than 60 pounds to tho square inch, and 
as a rule, this varies from 18 to 30 pounds, 
whereas tho steam that impels a high-pressure 
engine has a tension of 50 pounds and upwards 
to the square inch. 
The cylinder of tho engine is tire work-room in 
which tho steam performs all its labors. These 
are of tho simplest kind, and merely consist in 
pressing alternately against each side of a strong 
metallic dhsc, called the piston, lilted so accurately 
into tho polished cylinder, as to move to aud fro 
with a minimum of friction, and yet permit no 
steam to escape from ono side to the other 
round its edges. The force of this pressure iB 
proportionate to the dtnsity of the steam for, 
like all other gases, tho closer its component 
atoms are brought together tire greater is thoir 
tendency to fly asunder, and the stronger thoir 
pressure on all restraining surfaces. By it the 
piston is driven backward and forward in (be 
cylinder, as live steam from tho boiler is alter¬ 
nately admitted Into each end of It, at the same 
time that the steam which has j ust impelled the 
piston escapes into the condenser, in condens¬ 
ing, or into the open air, in non-condensing 
engines. Tho motion thus produced is trans¬ 
mitted to the machinery to be driven by the 
instrumentality of the piston-rod—a strong, 
metallic bar att ached to tho piston at one end 
and at tho other connected, either directly or by 
means of various intermediate contrivances, 
with the machinery to bo put in motion. This 
reciprocating movement of the piston is there¬ 
fore tho essential feature in all engines, and all 
tho complex mechanism that is so very likely to 
bewilder tho observant novice Is merely designed 
to produce and regulate this to the best ad¬ 
vantage. 
Tho cylinder is commonly of the toughest 
cast-iron, and to iusuro sufficient stiffness to pre¬ 
serve its form, is made much thicker than is 
required for strength. To prevent radiation of 
heat from the steam in it and consequent loss of 
power, it is generally inclosed in a covering or 
jacket of felt, wood, or other non-conducting 
material. The same end is attained by the 
retention of a layer of steam between it and an 
outer metallic casing, aud not uufrequently 
steam, felt aud wood are superimposed. In tho 
cyliuder-lread is inserted a stuffing box, through 
which tho piston-rod passes, and this is indented 
by an annular groove into which is forced a 
packing, usually of hemp, which presses so 
closely against the vibrating piston-rod as to 
prevent any leakage of steam out of the cylinder 
or of air into it. At each t-ud of the cylinder- 
are openings called “ports” for the entrance 
and exit of tho steam. The movements of this 
are controlled by valves contained in a strong 
casing set beside the cylinder. These valves 
are so worked by a part of tho mechanism of 
the engine, that when the induction or steam 
valve admits live steam into one end of tho 
cylinder, the eduction or exhaust valve is opened 
to allow the free exit of the spent steam at the 
other. 
In non-condensing or high-pressuro engines, 
this is 1 arced out by the returning piston against 
an atmospheric pressure of 15 pounds to tho 
square inch, aud the fresh steam propelling the 
piston must possess that amount of energy in 
addition to the power needed to operate the 
machinery to he driven, aud the special mechan¬ 
ism of the engine. Moreover, the orifice for tho 
escape of the steam can never be so largo us the 
cylinder that contains it; hence the steam m 
advance of the piston, is necessarily compressed 
and requires a proportionately greater force to 
expel it. Iucondonsing or low-pressure engines, 
on tho other band, tho spent steam rushes off 
through a short exhaust pipe into the vacuum 
created in the condenser by the joint action of 
an air pump and a constant spray of cold water, 
which instantly condenses it. Owing to the 
time required by the steam to escape through 
valve aud passage into the condenser, however, 
a perfect vacuum is unattainable, so that therois 
always a sensible back-pressure in advance of 
the piston. In condensing enginep, however, 
this is so feeble, that after it has been started 
the engine can be worked with a pressure of 
less than one atmosphere. 
Tho condenser is a steam and air-tight vessel 
set in cold water as near as possible to the 
cylinder, into which the Bpont steam passes 
during each movement of tho piston, and in , 
which, in tho jet condenser, it is at onco con¬ 
densed by a spray of cold water kept constantly 
playing there. In the surface condenser this is 
effected by tho admission of the steam into a 
collection of tubes surrounded with cold water, 
and not unfrequently both those means of con • 
densatiun are used at tho same time. The 
water injected to condense tho steam as well as 
tbut from its condensation, together with any 
air that may havo entered with it and also any 
residual steam are all extracted by an air-pump. 
Iu tho process of condensation the inherent 
heat of the steam raises tho temperature of the 
water in tho condenser, and this is dischaxged'by 
tho air pump into tho “hot well” whence a 
feed pump supplies ft sufficiency of it to the 
boiler to replace tho water taken up by vaporiza¬ 
tion, thus economizing a great deal of tbo boat 
lost in non-oondeneing engines by tho expulsion 
of tho spent steam into tho atmosphere. As au 
offset, however, to tho advantages of condensing 
engines they require an abundance of water, 
often not attainable, are considerably more ex¬ 
pensive than non-oondeuBing engines, while their 
mechanism is much more complex and their 
weight and bulk much greater. Moreover a 
considerable part of tbo power economized by 
them is diverted to work the cold-water pump 
which supplies the condenser cistern with cold 
water, and the air pump, both of which arc 
dispensed with in non-condensing engines. 
Tho lightness, compactness, and comparative 
cheapness of the latter, together with their econ¬ 
omical use of water,specially fit them for locomo¬ 
tive and portablo purposes, aud even for steam¬ 
boats, where economy of freight-room and light 
draught of water are important considerations. 
The thrust and pull movement a of tho piston 
arc converted into the rotary motion necessary 
for driving machinery, generally bv means of a 
crank affixed to tho working shaft, and connected 
either directly or by means of various interme¬ 
diate devices, with the piston-rod. The diam¬ 
eter of the circle through which this moves is 
equal to the length of tho stroke of tlie piston 
which is, indeed, determined by its movement. 
At the two points in its revolution answerable to 
the position of the piston at the end of each 
str oke, there is a momentary cessation of power 
and of the rotative impulse. These points are 
called tho “ dead points,” and theorankstanding 
at either is technically said to be “ on tka center 
Tho almost universal method of Bteadily contai¬ 
ning the movement over these dead points is by 
the application of a fly-wheel on tbocrank shaft. 
This is a heavily rimmed wheel, the inertia of 
which opposos any sudden accelerat ion of speed 
while its momentum, when it is onoo in motion, 
prevents any sudden diminution of it. Thus it 
servos as a reservoir of power to whirl the crank 
past tho dead points, aDd also efficiently aids t he 
governor in equalizing the speed of the engine. 
Another method of continuing uniformly the 
rotative irnpulso is by tbo uso of two cranks on 
tho same shaft placed at right angles to each 
other and impelled l>y apair of engines. By this 
arrangement at the moment that one crank is at 
either of tbo dead points, tho other is at that 
part of its revolution where the power of the 
engine is most effective and thus the oranks 
force each other alternately over the center. 
This is the principle utilized in locomotives which 
in reality consist of two engines, one to each 
cylinder, both of which are supplied with steam 
from a common boiler. 
At a convenient point in the pipe whioh conveys 
the steam from the boiler to the cylinder a 
throttle valve is placed, in form generally like 
an ordinary damper. Tho movements of this 
arc automatically coni rolled by tbo governor so 
that when the speed of the engine exceeds the 
desired rate the valve is partially closed aud the 
supply of steam to tho cylinder thus diminished. 
but when tho speed flags too much it is opened 
to allow free ingress to the steam, aud thus ac¬ 
celerate the movements of the piston on which 
the speed of the engine depends. Among tho 
maoy varieties of governors tbo * ’ fly-ball is the 
favorite. This consists of a pair of balls sus¬ 
pended from tho apex of a vertical epindlo which 
, . i _a v. *_ i _ _It_ 
steam at any desired part of tho stroke; a fixed 
expansion is so arranged as to cut off at a deter¬ 
minate part of tho stroke; both of these effects 
are produced by special expauion valves; but 
automatic expansion is regulated by tho governor 
and varies willi tho amount of power required to 
maintain » uniform speed. By this means steam 
and fuel are largely economized, for although the 
pressure of the steam decreases rajiidly after its 
supply is cut off, yet its expansion imparts a 
considerable power and this id obtained without 
tho expenditure of cither fuel or steam. 
The nieaeuro of the steam-engine’s power is 
known as its horse-power. This is a lifting 
power able to raiso 33,000 pound* ono foot high 
per minute. Watt considered this the average 
power exerted by a horse < i aveling at the rate 
of 2V, miles im hour, and raffing 150 pounds by 
a rope passing over a pulley, and iu substituting 
steam for horse-power us ft motor his calcula¬ 
tions wero made on this basis. Tho horse-power 
of an ongino now-a-davs has reference only to 
tho capacity of its cylinder in connection with a 
stated pressure of steam. w. L. h. 
(gntomolocjital. 
CONCUSSION 
GRASSHOPFERS. 
AMMONIA AS 
MOTIVE POWER. 
In view of the multitudinous inventions and } 
discoveries of the last century, it is among the p 
possibilities of the next generation or its succes- r 
sor that some means may bo devisid by which r 
tho vast energy inherent in gun-powder, nitro- t. 
glyceriue, gun-cotton, and other explosives shall t. 
be so restrained and regulated as to be as 1 
subservient to industrial purposes as steam is j. 
to-day. Electricity, solar caloric, compressed j c 
air, and ammonia, havo already been harnessed < 
as motors in the workshops of the industrial t 
arts, and the prophecy that these could thus be 1 
made serviceable would have bean considered as - 
extravagant among our great-grandfathers as t 
the other prediction ca n be among their descend- 1 
ants of this generation. ] 
From ono of our Australian exchanges we < 
loaru that tho employment of ammonia as a mo- 1 
tivo power is now attracting more than usual I 
attention there, partly iu consequence of the 1 
increased Bupply of crude material, and further. < 
because of the demand for somo substitute for < 
steam iu underground transportation and for < 
rapid transit through thickly populated thor- ■ 
oughfares. The feasibility of using ammonia- i 
engines has been conclusively proved by elabor- ; 
ate experiments, and the delay in their inlroduc- i 
tiou as a familiar motive power is a matter of 
considerable eurprffo among intelligent persons i 
who have examined into tbo subject. The 
principle on which ammonia gas is proposed as a 
motor is analogous to that upon which the use 
of steam is based. In tho ammomacal engine, 
tho expulsion of the gas from water aud its 
re-solution in tho water tako tho place of vapori¬ 
zation aud condensation of vapor In tho steam- 
engine. Tho rammer of operation of tho two 
descriptions of machines is so entirely similar, 
that but for tho corroding action of ammonia on 
all brass und copper boxes ami packing, and the 
loss of ammonia, they might he used inter¬ 
changeably. A steam-engine may bo converted 
into an ammonia engine by replacing with iron 
or steel tho parts constructed of braes, and by 
modifying to some extent the apparatus for con¬ 
densation. 
One of the earliest engines to be operated by 
ammonia was Invented by M. Frot of Taris, and 
was shown in 1867 at the French International 
Exhibition. It is fully described by Dr. Barnard 
in hid elaborate report on the machinery'of the 
Paris Exhibition. A fit teen-horse steam-engine 
was transformed into an ammonia engine by 
order of tho Emperor, and being alternately 
worked by etearn and by ammonia, it was possi¬ 
ble to make comparative experiments with all 
desirable exactness. Tho inventor claimed that 
its consumption of fuel per horse-power per 
hour, when working under ammonia, was not 
more than ono-third of that of a steam-engine 
working under similar conditions. That modi¬ 
fications mado by M. Frot in the condensing 
J apparatus wero only such as are necessary to re- 
dissolve the gas to a degree of saturation suffi¬ 
cient for repeated use and to return the solution 
X' ---- * _ . ViVUV ----- 
is caused to rotate by a cord driven by a pulley | 0 boiler. The same water and the earne 
on the fly-wheel shaft. The velocity with which gas were kept ia perpetual circulation, between 
it revolveB and the balls whirl round, ispropor- |, 0 jj er au d condenser, without any further loss 
tinned to the Bpeed of tho fly-wheel, uud the than was due to inevitable leakage. Tho report 
greater the speed the greater the centrifugal 0 f the commission appointed to examine this 
force and the farther the balls fly away from en gjne was in the main favorable, 
their supporting shaft. On this is a sliding ool- -- 
lar whioh ia moved up or down, as the balls DROUGHT AND THE SUCTION PUMP. 
collapse or expand, and the motion thus produced - 
opens or shuts the throttle valve by means of j T j g we q known that ordinarily a suction 
various ingenious devices. pump cannot draw water, under the most favor- 
Both high and low-pressure engines have been able conditions, from a greater depth than about 
worked on the expansive principle ever since the 33 feet. A column of pure water of this hight 
days of Watt who first discovered it. By it the weighs about 15 pounds to the Bquare inch, and 
supply of etearn from tho boiler to tbo Cylinder jg, therefore, equal to the pressure of the at- 
isent off when tho latter is only partially filled. Biosphere, on ft fine day, at the sea level. If a 
tho remainder of tho stroke of the piston bein '- small hole be made in tho suction pipe, however 
admitted. Thcro are thieo ways of effecting - of qp or cven 50 feet. The air admitted 
this. A variable cut-off can bo so adjusted, , mingles with the ascending current and dimin- 
while the engine is in motion, as to cut off the J islres its weight. 
It is well known that ordinarily a suction 
pump cannot draw water, under the most favor¬ 
able conditions, from a greater depth than about 
33 feet. A column of pure water of this hight 
weighs about 15 pounds to the square inch, and 
is, therefore, equal to tbe pressure of the at¬ 
mosphere. on a fine day. at the sea level. If a 
small hole be made in tho suction pipe, however, 
a few feet above tho snrfaeo of the well, the 
pump will readily discharge a stream from a 
depth of 40. or cven 50 feet. Tho air admitted 
mingles with the ascending current and dimin¬ 
ishes its weight. 
Con. Lucies A. Har dee of Florida, to whom 
we havo frequently referred in these columns as 
tbo originator of the scheme to destroy insect 
life by concussion, is out with a petition to 
Congress asking that body to test tho system on 
the grasshoppers of tbo Western States and 
Territories. Tbe Colonel is thoroughly in earn¬ 
est iu this matter, and we hope will be afforded 
an opportunity of blowing up the grasshoppers 
wherever they are found. In the petition re¬ 
ferred to he says: 
Some eight or ten years ago your petitioner s 
attention was called to tho destruction of his 
fruit crop by the curculio among his peaches, 
and scale insect among his orange trees, and 
caterpillar on his v ines. Your petitioner's farm 
is situated one mile from the city of Jacksonville, 
Florida, and known as Honeymoon Nurseries, 
and tho railroad runs through bis farm, and the 
trains approaching tbo city generally blow their 
shrill whistle in passing through his orchard. 
Your petitioner noticed that by night, or moon¬ 
light, tho cnreuHo was much frightened by tho 
noise, and concluded that severe concussion 
of tbo atmosphere was the natural enemy of 
these destructive insects, and that your peti¬ 
tioner bored with a common auger a hole in a 
live oak etump, in which he packed common 
gun - powder. That said stump was in his 
orchard, and that at night when tho air was 
dense and humid, ho caused with ft slow match 
the combustion of tho powder which produced 
heavy concussion of tho eir and ground. That 
your petitioner found next day to his surprise 
that nil the caterpillars on his vines had been 
lulled, which led him to believe that said cater¬ 
pillars wero destroyed by the eononssion either 
of tho ground or atmosphere, and that your pe¬ 
titioner afterwards experimented and has proven 
to many of his neighbors, ( whose testimony of 
the fact can be furnished), that concussion 
effectually destroys caterpillars. Your petitioner 
declares that concussion was, and is mnv an 
effectual remedy against tho ravages of insect, or 
parasite life in Florida, and that tho concussion 
under ground caused by tho combustion of gun 
powder will destroy frogs, mice, ground-mole 
and grubworm, Ac., Ac. 
Your petitioner on learning the fact that con¬ 
cussion could be utilized by the farmers and 
pomologies, called a publlo meeting of tho citi¬ 
zens of Jacksonville, iu r egard to tho above facta; 
and that said citizens accepted his theory of con¬ 
cussion, and that your petitioner attempted to 
obtain letters patent for his theory, hut failed 
in bo doing. That said concussion is now being 
used in Florida aud Louisiana for tire destruction 
of the scale insect, Ac., uud in Austria and 
1 France for the destruction of Phylloxera or 
Grape Louse. Your petitioner met the Borno¬ 
logical Society of the Baited States, convened at 
Richmond, Va. Marshall P. Wilder, was it 3 
President, in September, 1868- Tbe facts and 
proofs were laid before ft committee of said 
society, and said committee and society re¬ 
ceived favorably tbe facts and called it Hardee's 
theory of concussion. 
Your petitioner is perfectly sanguine that it 
takes but little concussion of the ground to 
destroy all the eggs of tho locust, and that if an 
experiment of heavy concussion of tho atmos¬ 
phere is brought about when the atmosphere is 
dense and humid,* that miles of the dense clouds 
of grasshoppers of tho West can be destroyed by 
one concussion. Your petitioner also claims 
that in seasons of great drought he can produce 
rain in twenty-four hours by concussion. and for 
proof of this will state that nearly in every 
instance after great battles in the late war there 
were copious showers la twenty-four hours, and 
in every instance it rained in less than forty- 
eight hours. Your petitioner also claims that if 
ho can prove that concussion will destroy insect 
1 or parasite life, then if the theory laid down by 
scientists that yellow fever and all contagious or 
infectious diseases are caused by animalcule is 
, correct, concussion will destroy these diseases. 
In proof Of this will state that no yellow fever or 
other contagion appeared in any of tho Southern 
cities Bubjocted to heavy concussion during the 
1 late war. 
Your petitioner claims that in a very recent 
experiment of concussion a stone jar was broken 
some three hundred feet from the cannon used, 
and panes of window glass wero shattered at a 
i great distance, and he is led to believe that any 
. concussion that will do this will certainly destroy 
t the thin gauze wings of tho Western grasshopper, 
t and again begs of your honorabl • body that he 
1 be allowed to use heavy concussijn against the 
great plague of the WeBt, the locust or grass- 
v hopper, all of which is respectfully submitted, 
, and your kind action in the premises earnestly 
3 solicited. 
From the above it will be seen that Col. Har- 
* Col. 11. seems to overlook the fa< 
phere is must dense when dry. [hi>. 
that the atmos- 
