General Ethical Dilemmas

Many of the general ethical dilemmas which arise in relation to genetic testing are not exclusive to this technology. As with all new developments in medicine, it is an ethical requirement that genetic tests are of proven safety and efficacy and that the benefits outweigh the risks and burdens before they are introduced into routine clinical practice. The stage at which technology moves from research to clinical application is as much an issue for genetic testing as it is for new treatments for cancer or heart disease. Those who believe that humanity exists as part of a divine plan may object to genetic testing on the basis that it seeks to interfere with natural processes or is a further manifestation of human hubris. Doctors are frequently accused of playing God'. If this were to mean that humankind should refrain from decision making about life or death, almost every kind of medical intervention would be precluded. We, however, be able.to draw boundaries which separate inter-. vent ions which are justified from those which are not. People who do not accept an absolutist religious position may nevertheless be unhappy about the attempts of humans to take ever greater control over their lives and the lives of their off spring. While we must accept that society has probably now lost the concept of children being born 'as nature intended', the continual striving for new developments in medical technology and ways of prolonging and improving life can sometimes manifest itself in what seems to some an almost obsessiveness for immortality or control. From another perspective, however, it has been suggested that increased genetic self awareness 'will help bring about the more rational attitude towards the inevitability of death of which modern societies (and healthcare systems) are in great need'.

Level of support for the child

There are concerns that as prenatal diagnosis becomes more widespread, those who decide not to have testing when they are known to be at risk of a genetic disorder, or who decide to continue with an affected pregnancy, may come to be seen as irresponsible. Where the child will be severe ti disabled and require long term and expensive treatment it is possible that society will become increasingly unwilling to pay for the necessary care, seeing the parents as 'to blame' for the birth and therefore individually responsible for the cost of treatment. In the USA there have been reports of private insurance companies attempting, unsuccessfully, to withhold reimbursement for medical care of children whose disability was detected before birth." With the increasing use of private medical insurance in the UK it is possible that a similar path may be trodden in this country. Any such moves must be vigorously opposed. The availability of resources for the care and treatment of a disabled child must not be contingent on whether the parents knew of the disability before the child was born.

Media perceptions

The media  naturally preoccupied with how genetic advances will affect people's lives in a dramatic manner.By concentrating on issues like genetic engineering or Cloning, they:seldom. mention how advances. in genetic technology may offer affected by genetic problems the only hope of attaining a reasonable standard of health or a normal lifespan.It transportation to allow the extreme or exceptional aspects of medicine's potential to dominate current debate in a way that obscures emote immediate goals of genetic technology.Whilst recognizing the poet.initial, for misuse,should,not lose sight of low.practice within genetic services focuses, on mitigating the tragic ace. of genetically transmitter.13etter ways of managing genetic conditions are, in the MBA's view, the main purpose And rationale of this technology.

The Wedge

The wedge is a kind of inclined plane. The difference is that an inclined plane stays in one place, but a wedge moves. One common use of a wedge is for splitting logs to make firewood. Wedges are sometimes used under doors to prevent them from blowing shut. The Egyptians may have used wedges to split the rocks that were used in building the pyramids. By hammering several wedges into a crack between two layers of rock, the rock could be weakened. Eventually the rock would split. 

The Screw

The screw is similar to the inclined plane and the wedge. It is an inclined plane that is rolled up. You can see this if you cut a right-angle triangle of paper, darken the long side, and roll it around a pencil as shown in the drawing. The pattern that results is much like the thread on a screw. If the inclined plane has a gentle slope, the thread will be fine. If the slope is steep, the thread will be coarse. You can follow the edge of the paper around the pencil with your finger and see how it makes a spiral. Screws are used to join pieces of wood or metal. When you use a wood screw, you apply a turning force to the screwdriver with your hand and wrist. As the screw turns, the threads pull the screw into the wood. In other words, a screw changes a turning force into a pulling force. Threads have many uses. The lids of jars and pop bottles are often threaded so that they can be closed tightly. Bolts and nuts depend on threads for doing their task of holding things together.

The Pulley

The pulley is a wheel that turns around an axle. A groove in the edge of the wheel allows a rope to pass over it or under it without slipping off. There are two kinds of pulleys fixed pulleys and movable pulleys. In a fixed pulley, the wheel turns but the arm holding the wheel is fixed in one place. A movable pulley moves up or down while the wheel turns. 

Sometimes the two kinds of pulleys are combined. The drawing at the left on the next page shows one fixed pulley and one movable pulley, used together to lift a load. The load is easier to lift this way than with a single fixed pulley. In fact, you can overcome a resistance of 50 N in this way with an effort of only 25 N. A block and tackle uses two fixed pulleys and two movable pulleys. With this combination, you can overcome a resistance of 100 N with an effort of 25 N.

The Wheel and Axle

 A wheel and axle machine is just that a wheel fixed to an axle, like the steering wheel of a car. When a steering wheel is turned, the axle, or shaft, turns with it. It would be impossible to turn the steering axle by grasping it in your hands. The wheel that is attached to the top of the axle makes steering possible. By grasping the rim of the wheel, the driver can easily apply enough force to turn the axle. The doorknob is another common example of the wheel and axle machine. As with the pulley and the lever, the advantage of greater force is matched by a disadvantage of increased distance.

The Lever

The lever may have been the first machine man learned to use. Cavemen almost certainly knew how to move a heavy rock with the help of a strong pole. All they had to do was to force one end of the pole under the rock and put a smaller rock on the ground under the pole near the same end. By pushing down on the other end of the pole, they could raise the rock. 

About 4000 years ago, the Great Pyramid was built in Egypt. It took about 30 years to build. There is no record of how it was built, but the lever may have been the principal machine used. Great teams of workmen may have levered the massive blocks of limestone out of quarries (workweek), dragged them to the site of construction, and then used inclined planes built of sand to raise them up onto the pyramid. Each block has a mass of about. Today, levers are more popular than ever. They are used in many household tools, such as scissors, pliers, the crowbar, and the claw hammer. 

Simple Machines

There are just six kinds of simple machines. Each kind has many uses. Big machines are merely many simple machines put together. The six kinds of simple machines are the lever, the pulley, the wheel and axle, the inclined plane, the wedge, and the screw.

The Meaning of Work

In everyday conversation, we use the word work in various ways. "Going to work", "doing homework", "a writer's work" these are some common expressions using the word. The meaning of "work" varies. But, to the scientist, "work" has the same meaning every time it is used. In science, we say that "work" has been done only if a force of some kind has moved an object from one place to another place. "Work is done when a force moves an object through a distance" is how scientists describe it. 

You are doing work, in the scientific sense, if you lift a bag of potatoes onto your shoulders. You use a force to raise the bag through the distance from the floor to your shoulders. Once the bag is on your shoulders, no more work is being done because there is no motion. The amount of work you did depends on the amount of force you had to use and the distance through which you moved the potatoes. For example, you do work whenever you stretch a spring or an elastic band. The more you stretch it, the more work you do.

Machines 

The modern world is filled with machines. Some of them are very simple, such as the can opener, the shovel, and the saw Others are more complicated, such as the bicycle, the lawn-mower, and the crane. All machines are designed to make work easier. There are three ways in which they can do this by increasing the force, by increasing the speed, and by changing the direction of the force. Here is an example of each of the three ways.

Musular Force

Muscles make it possible for animals to move. They are attached to the bones. Most muscles are controlled by the brain. Messages from the brain travel through nerves and tell the muscles when to act. Unused muscles go soft. Exercise and a proper diet that includes lean meat, milk, and cheese help to build strong muscles. 

The force Of Friction 

When two surfaces are rubbed against one another, one tends to stick to the other. Friction is the force that causes this. No surface is perfectly smooth. Even the smoothest looking surface, when examined with a microscope, will be seen to have bumps and hollows. These bumps and hollows resist one another when two surfaces are rubbed together. The force of resistance is called friction. Friction can be useful. Rub the palms of your hands together, pressing hard. Do this quickly several times. Your hands begin to feel warm. This shows that friction produces heat.

What Can Forces Do?

Forces can make things move. They can also act on stationary objects without causing motion. Sometimes we use a force on an object that is already moving, to stop it. A train uses a braking force as it approaches a station. Similarly, when astronauts were about to land on the moon, rockets were used to slow down their craft, so it could make a soft landing. Forces can also change the direction of motion. This happens in baseball when a batter hits the ball. The ball is first slowed down, then stopped for an instant, then shot off in a different direction. 

 The Force Of Gravity

This is the force that pulls objects down to the ground. when we say a rock is heavy, we mean that the force of gravity pulling down on it is a strong force. To lift the rock off the ground, you must use a force that is slightly greater than the pull of gravity. Once the rock is moving upwards, the lifting force becomes equal to the gravity force. The force of the Earth's gravity is what holds the moon in its nearly circular path around the Earth and prevents it from flying off into outer space. Similarly, it is the force of the sun's gravity that keeps the Earth and the other planets in their orbits.

Culture Media

A culture medium must contain a balanced mixture of the required nutrients, at concentrations sufficient to allow a good growth rate. If a nutrient is in excess, it can inhibit growth or even be toxic. Often one nutrient is present in limiting quantities, to allow adequate growth while preventing the microorganisms from multiplying at their maximum rate. By moderately slowing down the growth rate, the microorganisms are kept healthy. Usually a mineral base is made, containing all the possible nutrients in inorganic form. To this can be added a carbon source, energy source, nitrogen source and growth factors, to suit the organism being cultured. A medium composed entirely of chemically defined nutrients is called a synthetic medium. A medium which contains some ingredients of unknown chemical composition, such as malt extract, is called a complex medium.

Reptiles

Crocodiles, too, regulate their body temperature on land by varying their position relative to the Sun's rays. They also open their mouths to increase heat loss by evaporation. If the temperature becomes too high, they move into the water which is relatively cooler. At night they retreat to water in order to avoid the low temperatures which would be experienced on land. Regularization mechanisms have been studied most extensively in lizards. Many different species of lizard have been studied and show a variety of responses to different temperatures. Lizards are terrestrial reptiles and exhibit many behavioral activities, as is typical of other isotherms. Some species, however, use a number of physiological mechanisms to raise and maintain their body temperatures above that of the environment. Other species are able to keep their body temperature within confined limits by varying their activity and taking advantage of shade or exposure. In both these respects lizards foreshadow many of the mechanisms of thermometer shown by birds and mammals. 

Surface temperatures in desert regions can rise to 70-80 °C during the day and fall to 4 °C at dawn. During the periods of extreme temperatures, most lizards seek refuge by living in burrows or beneath stones. This response and certain physiological responses are shown by the horned lizard (Chromosomal) which inhabits the deserts of the south-west of the USA and Mexico. In addition to burrowing, the horned lizard is able to vary its orientation and color, and as the temperature becomes high it can also reduce its body surface area by pulling back its ribs. Other responses to high temperatures involve panting, which removes heat by the evaporation of water from the mouth.

THE SKELETAL SYSTEM

The 206 bones of the body make up a working whole called the skeleton, or skeletal system. Together, the bones of the skeleton perform many important functions, some of which have already been mentioned. To summarize:The skeletal system provides support for the body otherwise you would be a shapeless blob of skin covered tissues and organs. It also provides for movement, with individual bones serving as points of attachment for the skeletal muscles and acting as levers against which muscles can pull.Delicate internal structures are protected by the skeleton. The brain, for example, lies within a strong, bony casing called the skull; the rib cage surrounds and protects the heart and lungs.The bones of the skeleton are a storehouse for minerals such as calcium and phosphorus.

Amazingly, bone tissue is continually broken down and reformed, the mineral salts being transported to other parts of the body on demand. In fact, scientists have estimated that your body completely "replaces" your skeleton over a period of 7 years! Lastly, certain inner portions of bones contain red marrow and arc your internal factory of blood cells. Without this factory you would die, since red blood cells have a short life span of approximately 120 days. Without these cells your body would have no efficient means to transport life giving oxygen to your tissues. 'White blood cells are also produced in the red bone marrow. One of the main jobs of certain classes of these cells is to ingest bacteria and debris.

Archaeal Genomes Combine Features Of Bacteria and Eukaryotes

Like bacteria, Archean have polytechnic opens, and their reproduction is predominantly asexual. Archean are true protectorates in that their cells lack a nuclear membrane. On the other hand, in most species of Archean, the structures of the DNA packing proteins, RNA polymer, and chromosomal components more closely resemble those of Prokaryotic. Even the DNA polymer and the origin recognition sequence show greater similarity to those of Prokaryotic. Finally, it should be noted that charcoal genomes encode certain unique components such as the metabolic pathway of parthenogenesis. Carbon Trading news in freshsciencenews For more on Archean, What experimental data allow us to make such comparisons? Overwhelmingly, we rely on new data from the growing number of microbial genomes sequenced. Comparison of genomes has revolutionized our understanding of evolutionary relationships among microbes. We will now examine the tools of DNA sequence analysis that have made these studies possible. The most important of these tools restriction mapping, DNA sequencing, and amplification by the polymer chain reactionactually harness the molecular apparatus used by bacteria to replicate or protect their own chromosomes. 

DNA Sequence Analysis 

We have just described the core concepts of DNA structure, packaging, and replication. This knowledge is crucial to understanding genomics and the fundamentals of gnomic analysis. It is now appropriate to discuss the basic techniques used to manipulate DNA. These include isolating gnomic DNA from cells, snipping out DNA fragments with surgical precision, splicing them into plasma vehicles, and reading their polynucleotide sequences. These are the techniques that drove the gnomic revolution.

study of behaviour (ethology)

Behaviour may be defined as the outwardly expressed course of action produced in organisms in response to stimuli from a given situation. The action modifies, in some way, the relationship between the organism and its environment and its adaptive significance is the perpetuation of the species. All living organisms exhibit a variety of forms of behaviorism activity deter-mined by the extent to which they are able to respond to stimuli. This varies from the relatively simple action of the growth of a plant stem towards a light source, to the complex sexual behavior patterns of territory defense, courtship and mating seen in birds and mammals. Plant behavior is restricted to movements produced by growth or turgid changes and is stereotyped and predictable. The two main activities associated with plant behavior are tropisms and taxes and details of these are described in section. Animal behavior is far more complex and diverse than plant behavior and therefore it is extremely difficult to investigate and account for with any degree of scientific validity. The three main approaches to behavioral studies are the capitalistic, mechanistic and ethological approaches. 

Vitalistic approach

This seeks to account for behavioral activities in terms of what animals are seen to do, and attempts to relate this to changes in the environment. It involves the total rejection of any study of the animal outside its natural environment. The technique has its foundations in natural history and has provided a wealth of valuable data, but it is essentially non scientific since all the observations relate to past events which cannot be tested experimentally.

The meninges and cerebrospinal fluid....

The central nervous system is surrounded by three layers or 'membranes' called meninges  and is completely encased within the protective bones of the skull and vertebral column. The outer membrane forms the tough dun mater which is attached to the skull and vertebrae, and the inner membrane forms the thin Pia mater which lies next to the nervous tissues. Between the two is the arachnid 'membrane'. This includes a space, the arachnophobia space, strands of connective tissue, blood vessels and cerebrovascular fluid (CS). Most of this fluid is contained in the central canal of the spinal cord and continues forward to occupy four expanded cavities within the brain called the ventricles. The fluid therefore comes into contact with the outside and inside of the brain, and blood vessels lie within it for the supply of nutrients and oxygen to the nervous tissues and the removal of wastes. It also contains lymphocytes to protect against infection. Meningitis is caused by an infection of the meninges. About 100 cm3 of fluid is present in the CNS and, apart from its nutritive, excretory and defensive functions, it supports the nervous tissues and protects them against mechanical shock. A continual circulation of fluid is maintained by cilia ted cells lining the ventricles and central canal. 

The Spinal Cord

The spinal cord is a cylinder of nervous tissue running from the base of the brain down the back. It is protected by the vertebrae of the backbone (vertebral column) and the meninges. It has a shaped central area of grey matter, composed of nerve cell bodies, dendrites and synapses surrounding a central canal which contains cerebrovascular fluid. Around the grey matter is an outer layer of white matter, containing nerve fibers whose fatty myelitis sheaths give it its characteristic color. There are 31 pairs of spinal nerves and these divide dose to the spinal cord to form two branches called the dorsal root and ventral root. 

 

The hip and thigh

The lower limb, similar in structure to the upper, is modified by its functions of support and propulsion of the body. During its development there is rotation medially on its long axis, so that the flexion surface lies posterior and the sole of the foot faces backwards and then downwards. The pelvic girdle, unlike the pectoral girdle, is firmly attached to the vertebral column, which allows the transmission of the body's weight through it to the lower limb. In the standing position the center of gravity passes behind the hip and in front of the knee and ankle joints. The weight is distributed between the heel and the balls of the toes, most of it being carried by bones and ligaments, with only a minimal amount of muscle activity being required to maintain balance.

The Deep Fascia

 The deep fascia of the gluten region and thigh forms a investigating layer, the fascia lats, from which medial and later inter muscular septa divide the thigh muscles into distinct com departments. Proximal it is attached in a continuous line to the inguinal ligament, lilac crest, posterior sacrum, sacra tuberous ligament, Islamophobic rams and the body of the pubic . Three centimeters below and 1 cm lateral to the pubic tubercle an oval deficiency in the fascia, the sousaphones opening, transmits the great sousaphones vein. The fascia lam is thickened on the lateral side of the thigh, the tibial tract, which is attached distally to the lateral tibial cotyledon. Glutenous maxims and tensor fascias latte gait Impeachment to the tract. Thus they may assist in extension and mobilization of the knee. Over the political fossa the fascia is by the small sousaphones vein. The fascia a is rather like a pair of women's tights.

The ear,intracranial region and cranial nerves

The organ of hearing and balance is divided into an external ear, conveying sound waves to the tympanic membrane; a middle ear relaying the membrane's vibrations to the internal ear; and the cochlea of the internal ear, which translates these vibrations into nerve impulses. The semicircular canals, the organ of balance, are also in the inner ear. The external ear consists of the auricle (pinny) and the external acoustic meats. The auricle is formed of an irregularly shaped piece of cartilage covered by firmly adherent skin. It has a dependent globule used for earrings and an anterior Travus which projects and overlaps the opening of the menus. The external acoustic meat us (SEAM) passes almost horizontally from the Travus to the tympanic membrane in a slightly anterior direction. It is about 4 cm long. Its cartilaginous lateral third is continuous with the cartilage of the auricle; the bony medial two-thirds are formed mainly by the temporal bone. The meat us is lined by skin containing many wax secreting (coterminous) glands. It is innervated by the horticulturalist nerve anterior and the vague nerve posterior. The translucent tympanic membrane (eardrum)  separating the external and middle ears is oval in shape and lies obliquely, with its outer (lateral) surface facing down-wards and forwards. The handle of the mallets is attached to its medial surface and produces a small elevation on the drum, which can be seen with an periscope as the dumbo. 
 
 The middle car (tympanic cavity;  lies within the temporal bone. It is about 15 mm high, 15 mm long, and its medial and lateral walls curve inwards, being about 2 nun apart in their middle and 6 mm apart at the roof. The cavity, lined in part by cilia ted columnar epithelium, contains three small bones, mallets, incs and spates  the auditory vesicles. The lateral wall is formed mainly by the tympanic membrane. Above and behind the membrane is an upward extension of the cavity, the tympanic recess, which contains part of the mallets and incs. The medial wall has a central bulge, the promontory, overlying the base of the cochlea (see below). Above and behind it is the fenestration vestibule (oval window) and below it the fenestration cochleae (round window). Both these formalin lead to the inner ear. The fenestration vestibule is closed by the footplate of the states and the fenestration cochleae by a fibrous membrane. The anterior wall has two openings, the upper for tensor tympani muscle, which attaches to the handle of the mallets, the lower for the auditory (Eustachian) tube, which communicates with the pharynx. High on the posterior wall is the audits, the opening into the mastoid ant rum. Below it formalin transmit the stampedes muscle to the spates and the chords tympani. The facial nerve grooves the medial wall and then descends the medial and part of the posterior wall in a bony canal.

GASEOUS EXCHANGE IN A MAMMAL

Structure of the respiratory system

The respiratory surface of a mammal consists of many air sacs called alveolar inside a pair of lungs. The lungs are situated next to the heart in the thoracic cavity and arc connected to the atmosphere by tubes. Air passes into the lungs through these tubes. Twelve pairs of bony ribs surround and protect the lungs and heart. intercontinental muscles are attached to the ribs, and a large diaphragm separates the thorax from the abdomen.

These are involved in the ventilation mechanism, as described in section. Air enters the body through two nostrils, each of which possesses a border of large hairs which trap particles in the air and filter them out of the system. While passing through the nasal passages the air is warmed and moistened and its dour detected. Air passes from the nasal passages, through the pharynx and into the trachea. This is a tube which lies in front of the esophagus and extends into the thoracic cavity. The wall of the tube is strengthened and held open by horizontally arranged C-shaped bands of cartilage. The open section of the C is next to the esophagus. The cartilage prevents collapse of the tube during inspiration (breathing in). The cartilage can be seen in a section of the trachea. At its lower end the trachea splits into two bronchi. Within the lungs each bronchus subdivides many times into 

much smaller tubes called bronchi oles. These in turn branch into finer and finer tubes, ending with the alveolar ducts which lead into sacs called alveolar sacs. Into each alveolar sac opens a group of alveolar. A summary of these structures and their main features is provided in. The walls of most of the respiratory passage are lined with cilia ted epithelial cells and goblet cells, which secrete mucus. Mucus traps any particles, such as dust and bacteria, that have managed to pass through the hairs of the nostrils. The beating of the cilia then carries the trapped particles to the back of the buccaneer cavity where the mucus is swallowed. Note that it is not the cilia which trap the particles don't confuse them with the hairs in the nose. Mucus also moistens the incoming air. 

Flowers Fruits And Seeds

Flower  that is, those that are beautiful or fragrant, or both  have always had a strong appeal for mankind. Poets of every age have praised them. Roses, tulips, gladioli, azaleas, chrysanthemums, phlox and a host of other plants are cultivate for their showy flowers. Experts are constantly seeking to improve upon nature by making blossoms larger, more showy and more fragrant. The arrangement of flowers is an esteemed art. In the scheme of nature, however, a flower is more than an object of beauty. It is a reproductive organ, by means of which a plant carries on its kind. The most beautiful and fragrant of the flowers are concerned with this task. So are inconspicuous flowers, such as those of the ragweed, and ill smelling flowers, such as we find in the skunk cabbage and the Dutchman's pipe. The only plants whose reproductive processes are centered in flowers are the angiosperms, or flowering plants, which are the most highly evolved of all. In the flowers of angiosperms, as in the reproductive organs of the higher animals, a new organ-ism arises when an egg is fertilized by a sperm. There is an important difference, however. In the higher animals the re-productive organs produce the sex cells eggs and sperm directly. The reproductive organs of flowering plants produce spores first; then egg and sperm cells develop from the spores. The visible plant of an angiosperm  an oak tree, or a rose bush or a lilac represents the spore producing stage. The sexual stage is rep-resented only by the short span between the formation of spores and the production of sex cells by the spores shortly after their formation. Each flower originates in a bud, just as leafy  shoots do.various sequestration methods science daily. In the leafy shoot, leaves arise in the bud as minute projections at the sides of a dome shaped or slightly flattened stem tip, or growing point. In many plants the same stem tip that forms leaves changes later into a floral structure. It produces the small lateral  projections that will develop into floral organs, in much the same way that it formed the young leaves. What determines whether a plant will put forth leaves or flowers? Various factors are involved. To yield flowers there must be ample stores of food in the plant, in the form of proteins and carbohydrates. Likewise certain hormones, called florins, must be produced. Florins arise in many plants after a certain age has been reached. In such cases the plant turns to flowering after it has produced a certain number of leaves. 

                          

Heat Engines

MAN'S puny strength would never suffice to accomplish all the tasks that his fertile brain suggests. To help him perform these tasks, he has provided himself with a variety of power sources  heat, wind, water flowing downhill, electricity and, within recent years, the splitting of atoms in nuclear reactors. Heat is among the most useful of these sources of power. It drives most land vehicles (passenger automobiles, trucks, locomotives, tractors), marine craft (ocean liners, freighters, warships, motorboats) and aircraft (propelled planes, turboprops, turbojets, rockets). It serves to generate electricity in power stations and on farms. It operates blowers, pumps, certain types of fans and many other devices. In all heat engines, the chemical reaction that takes place when fuel is burned imparts a high degree of kinetic energy (energy of motion) to countless gas molecules. Generally these particles strike certain movable parts, such as pistons or the vanes of turbines, and these movable parts provide driving force. In the case of certain airplanes a forward thrust is produced as expanding gas is expelled from a nozzle set at the rear of the plane. 

An ancient Greek mathematician and physicist, Hero of Alexandria (we do not know just when he flourished), was prob-ably the first to show that heat energy could be used to perform work. He invented a steam engine called the Paleolithic , which worked on much the same principle as a modern rotary lawn sprinkler.A high return on capital tilts the kids science magazines. This engine consisted of a globe mounted between two tubes projecting upward from a steam boiler. The bent upper ends of the tubes passed through holes in the globe, which could rotate freely. Two bent nozzles were attached at opposite sides of the globe. The water in the boiler was heated the steam passed from the boiler through the upright tubes into the globe and then out through the bent nozzles attached to the globe. The reactive force of the steam issuing from the nozzles caused the globe to spin rapidly. Hero never put his Paleolithic, which was a form of steam turbine, to any practical use.