Stephen Hales
Stephen Hales ( born September 17 or September 7, 1677 at Beckesbourn, Kent; † January 4, 1761 in Teddington, Middlesex ) was an English physiologist and physicist.
Family
Hales was baptized on September 20, 1677. From a total of eleven children, he was the sixth and youngest son, from the marriage of Thomas Hales, the eldest son of Sir Robert Hales ( ennobled under Charles II), and Mary, daughter and heiress of Richard Wood ( Esquire ), Abbotts Langley ( Hertfordshire), emerged. A younger branch of the Hales of Woodchurch family was descended from one of the oldest and most prestigious families of Kent, which can be traced back to the 11th century and a series of extraordinary personalities brought forth (such as in the 16th century: Attorney-General, Vice-Chancellor, barons ).
At 43, he married Mary Newce, the daughter of the Rector of Much Hadham, but a year later his wife died, probably in childbirth.
Stephen Hales died after a brief illness at the age of 84 years and was buried for customization at the foot of the new church tower of Teddington ( a monument located in Westminster Abbey ): " I desire no other reward than the greatest of all rewards that I enjoy: . to have the joy of doing something for the good of humanity " (Stephen Hales 1760)
Education and work
About his childhood little is known except that he " properly taught in grammar " in Kensington and Orpington was. After the early death of his father took over his grandfather, Sir Robert Hales, the education of boys and enrolled him in June 1696 on Bene't (St. Benedict ) College (later Corpus Christi College ) Cambridge University for the study of theology with the goal of a priesthood of the Anglican Church. After obtaining the initial study degree Hales was incorporated in February 1703 as a Fellow of the College, the same year he finished his studies (MA) and was ordained a deacon.
Played an important role at that time the scientific school of the University of Cambridge, which was significantly dominated by the physicist and mathematician Isaac Newton, who worked until the end of the century at Trinity College. Another influence that Hales zuführte the scientific field, came from William Stukeley, who was admitted in 1703 as a student of medicine at the College. He was a small room available where he could perform a variety of experiments ( physics, chemistry, botany, anatomy, etc.). Hales made friends not only with the much younger Stukeley to, but soon began to be interested in its work. Together they heard lectures of the astronomer Roger Cotes, experienced the chemical experiments of John Francis Vigani (* 1650, † 1712) in the laboratory of Trinity College with and roamed with the botanical catalog of John Ray in their luggage through the area surrounding Cambridge.
After the medical degree ( BM) Stukeley left Cambridge in 1709 to work as a doctor in Lincolnshire, as Hales, who completed his theological studies in August of the same year (BD), the priests ordained and as pastor of the small congregation Teddington ( Middlesex ), near located on the River Thames from London, was appointed. Here he remained until the end of his life.
The income of the parish in Teddington (then 500 inhabitants) were not very big. However, Hale had as a scion of a distinguished family enough private funds for his livelihood. In addition, he also received a benefice in Porlock ( Somersetshire ), which he in 1722 with the municipality of Farringdon, near Winchester, reversed. Here he spent most the summer months. Since 1719 the poet Alexander Pope lived near Teddingtons. Although Pope abhorred animal experiments and publicly expressed against animal cruelty, he appreciated very Hales.
Performance
Based on the physiology of muscle movement Hales managed the animal experimental determination of the arterial and venous blood pressure for the first time. Single-handedly, he was co-founder of plant physiology, inventor and pioneer of preventive medicine and is considered one of the founders of modern physiology.
Pastoral care and social work
In the community work, Hales tried particularly to public morality (eg punishment of adultery ), but also took care of the enlargement of the churchyard (1734 ), who built a new church tower and helped the community a viable water management ( 1754).
Hales also played an important role in the enforcement of state-controlled alcohol sales ( Gin Act 1736), since 1733 the uncontrolled consumption of alcohol in England had led to terrible social misery.
Colony of Georgia
Since 1732 Hales was a member of the founding committee of the American colony of Georgia. The idea of the colony was based initially on philanthropic vision: It was to meet the pauperism with emigration and thereby improve the social conditions of England, on the other hand, the opportunity arose to expand the British Empire to overseas territories. Until 1759, this private committee managed by England from the American province before they then passed into the possession of the British crown. Overall, however, were making political and commercial interests ( slave trade, etc.) in the foreground. The botanist John Ellis named a tree flora of Georgia in memory of Hales Halesia.
The work of the committee brought Hales also with problems of navigation in touch: He described measures for long sea voyages ( 1739 ), designed a ventilation system for ships, which was later used for hospitals and prisons ( 1743, 1758) and proposed a method for distillation of salt water before (1756 ). Its ventilation system was also a practical application, which emerged from the basic research on plant respiration and the rebreathing experiments on himself.
Science and Research
Hales and Stukeley conducted dissections of various animals from, made anatomical preparations (for example, wax cast of the bronchial system ), repeated chemical experiments (after corpuscular, not humoral principles ) by Robert Boyle and constructed a model of the solar system according to Newton's specifications ( Orrery ). Probably already at that time ( 1706) led by Hales first experiments to measure blood pressure in dogs. At the University, he had acquired knowledge of engineering fundamentals, but it was the friendship and work with Stukeley awakened his interest in biology.
Hales was initially engaged in the care of his church, but soon took his studies in experimental animals ( horses, dogs, sheep, deer ) to determine blood pressure again ( 1712-1714 ). In March 1718 Hales informed ( at the urging of Stukeley ) Newton as President of the Royal Society about his new experiments, the " ascent of sap in trees by the warmth of the sunlight " concerning. In the same year Hales was elected to the Royal Society ( FRS). The plant physiology was now his main area of research. The results of this work appeared in 1727 under the title Vegetable Staticks.
Many of his plant physiological experiments were of fundamental importance: he was concerned with quantitative studies of evaporation, determined the root pressure of the ascending juices, disagreed with the circuit hypothesis of plant sap, discovered the ability of plants to absorb gaseous substances and store and fell just short of the knowledge of the assimilation ability. He worked in numerous experiments with gases, which were bound in the various substances and which he freely placed by heating ( by Joseph Black as fixed air, fixed air called ), what it was leading to the investigation of respiratory and combustion processes in the animal organism. 1733 was followed by the publication of a summary of his animal physiology ( Haemastatics ).
Hales not only repeated John Hunters experiments on bone growth ( symphysäres growth), but also studied the growth of plants. He watched spinal reflexes in the frog (long before Robert Whytt, 1757) and probably discovered by chance in the context of its ventilation or Respirationsstudien the carbon dioxide. At the end of his life Hales returned again to animal physiology experiments back ( gills ).
First direct measurement of blood pressure
" In December, I had put a live mare on the back and tie. She was 14 hands high, about 14 years old, had a fistula on the side and was neither very lean nor overly blooded. After I had about 3 inches [ 75 mm] away exposed and open from the left abdominal Kruralarterie, I introduced a metal tube in the same, which is about 1/6 inch. Had [ 4.17 mm] diameter, to which I have a glass tube of about the same diameter but 9 feet [ 270 cm] length fastened by means of a precisely matching second metal tube. As soon as I loosened the ligature of the artery, the blood rose in the glass tube 8 feet 3 inches [ 240.75 cm] high. " (Stephen Hales 1733)
Hales began approximately in 1709 with experiments on circulatory physiology and blood pressure in animals. You have to imagine that he carried these years of trials in addition to his work as pastor of Teddington alone on his churchyard. It was not until much later ( 1733) appeared the written summary of its results.
The first attempt of a direct arterial blood pressure measurement was performed on a horse. Hales was the blood from the Kruralarterie rise in an approximately three -meter-high glass tube and determined the height of the blood column. Then he let the horse bleed something that caught the blood and repeated the blood pressure measurement. This experiment he repeated 25 times was bled ( at progressively decreasing blood pressure) until the horse. In the second experiment he conducted a similar arterial blood pressure measurement on a gelding. In the third experiment (horse) it first determined the venous pressure in the left jugular vein, then the arterial pressure in the left carotid artery, the volume of the left ventricle by means of injection of melted wax, the ejection fraction of the left ventricle, the velocity of the blood in the aorta, the degree of arterial dilatation with each heartbeat, the cardiac blood volume and diameter of the aorta. In this way, he realized that the blood pressure in the large vessels of two sizes was dependent: the cardiac output and peripheral resistance. On this occasion he also suspected that the increased diastolic filling is answered from the heart with an increased systolic ejection (see Frank -Starling mechanism ).
The following of the 25 experiments for comparative physiology of the circulation (horse, ox, sheep, different sized dogs ) dealt ( usually after an obligatory measurement of venous and arterial blood pressure ) with the cardiac output, the blood velocity in different parts of the arterial system, with blood pressure and velocity in the pulmonary artery, the influence of various liquids (for example, brandy ), and temperatures in the vessel status, with animal respiration and digestion and others.
In order to assess the difficult question of the cardiac ejection volume per minute and resting conditions, he counted the pulse rate of the animal before the start of the experiment, certain invasive venous and arterial pressure, left to bleed the animal and then injected ( with comparable pressure through a third cannula ) molten wax through the pulmonary vein into the left ventricle, which is then released into the glass tube at the carotid artery. After the wax was hard, he cut the cast of the left ventricle and certain volume and surface area of the same: "So that thus formed piece of wax quite the amount of blood that receives this ventricle at each diastole is appropriate, and then in the subsequent systole is driven into the aorta. " ( Hales 1733)
Awards and achievements
1733 Hales became a Doctor of Divinity. (University of Oxford) PhD. In 1739 he was awarded the Copley Medal of the Royal Society, and not for his pioneering physiological studies, but because of marginal importance to the dissolution experiments of kidney and bladder stones. In 1753 he was appointed foreign member of the Académie Français. Hales was co-founder of today's Society of Arts (Vice President 1755) and a good friend of the Prince of Wales.
Works
- Statical Essays: Containing Haemastatics; Or, An Account of Hydraulic and some Hydrostatical Experiments Made on the Blood and Blood - Vessels of Animals. London 1733
- A Description of the fan. London 1743
- An Account of a Useful Discovery to Distill double the usual quantity of Sea -water, by Blowing Showers of Air up through the Distilling Liquor ... and on account of the benefit of the fan. London 1756