Stephen Hales

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Dr. Stephen Hales
(ca. 1759)

Stephen Hales (September 17, 1677- January 4, 1761) was an English clergyman whose inventions, studies and experiments made major contributions to developments in botany, pneumatic chemistry and in both plant and animal physiology. He was the first to measure blood pressure utilizing his "Hales Manometer", and also invented a pneumatic trough to distill various "airs" i.e., gases. His other medical or health related inventions include a ventillation bellow to improve air quality in enclosed spaces, and surgical forceps for the removal of bladder stones. He was a philanthropist and wrote a popular tract on alcoholic intemperance.



Vegetable Staticks (1727)

, Or, An Account of Some Statical Experiments on the Sap in Vegetables: Being an Essay Towards a Natural History of Vegetation. Also, a Specimen of an Attempt to Analyse the Air, by a Great Variety of Chymio-Statical Experiments; Which were read at several Meetings before the Royal Society. A source.
  • And if we reflect upon the discoveries that have been made in the animal œconomy, we shall find that the most considerable and rational accounts of it have been chiefly owing to the statical examination of their fluids, viz. by enquiring what quantity of fluids, and solids dissolved into fluids, the animal daily takes in for its support and nourishment: And with what force and different rapidities those fluids are carried about in their proper channels, according to the different secretions that are to be made from them: And in what proportion the recrementitious fluid is conveyed away, to make room for fresh supplies; and what portion of this recrement nature allots to be carried off, by the several kinds of emunctories and excretory ducts.
    • The Introduction
  • And since in vegetables, their growth and the preservation of their vegetable life is promoted and maintained, as in animals, by the very plentiful and regular motion of their fluids, which are the vehicles ordained by nature, to carry proper nutriment to every part; it is therefore reasonable to hope, that in them also, by the same method of inquiry, considerable discoveries may in time be made, there being, in many respects, a great analogy between plants and animals.
    • The Introduction
Fig. 38 Pneumatic trough
Vegetable Staticks (1727)
  • We have from the foregoing Experiments many proofs of the very great and different quantities of moisture imbibed and perspired by different kinds of Trees, and also of the influence of the several states of the air, as to warm or cold, wet or dry, have on that perspiration. We see also what stores of moisture nature has provided in the Earth against a dry season, to answer this great expence of it in the production and support of vegetables; how far the dew can contribute to this supply, and how insufficient its small quantity is towards making good the great demands of perspiration: And that plants can plentifully imbibe moisture thro' their stems and leaves as well as perspire it.
    • The Conclusion
  • We have... many proofs of the great force with which plants and their several branches and leaves imbibe moisture, up their capillary sap vessels: The great influence the perspiring leaves have in this work...
    • The Conclusion
  • I have here, and as occasion offered under several of the foregoing Experiments, only touched upon a few of the most obvious instances, wherein these kind of researches may possibly be of service in giving us useful hints in the culture of plants: Tho' I am very sensible, that it is from long experience chiefly that we are to expect the most certain rules of practice, yet it is withal to be remembred, that the likeliest method to enable us to make the most judicious observations, and to put us upon the most probable means of improving any art, is to get the best insight we can into the nature and properties of those things which we are desirous to cultivate and improve.
    • The Conclusion

Philosophical experiments (1739)

: Containing Useful, and Necessary Instructions for such as undertake Long Voyages at Sea. Shewing how Sea-Water may be made Fresh and Wholsome: And how Fresh Water may be preserv'd Sweet. How Biscuit, Corn, &c. may be secured from the Weevel, Meggots, and other Insects. And Flesh preserv'd in hot Climates, by Salting Animals whole. To which is added, an Account of several Experiments and Observations on Chalybeate or Steel-Waters: With some Attempts to convey them to distant Places, preferring their Virtue to a greater Degree than has hiterto been done. Likewise a Proposal for cleaning away Mud, &c. out of Rivers, Harbours, and Reservoirs. Which were read before the Royal-Society, at several of their Meetings. A source.
  • I was at first much discouraged, when I reflected on my Rashness, in venturing on an Undertaking, which had baffled the repeated Attempts of the best Philosophers and Chymists, both Ancient and Modern: In so much that they looked upon it as almost impracticable to find out any way to procure a wholesome Drink from Sea-Water.
    • The Dedication

The Preface

  • I shall... give an Account of what has been formerly attempted for making Sea-Water drinkable, especially what was done by Mr. Walcot and Mr. Fitz-gerald in King Charles the Second's Time.
  • St. Basil, in his Homilies, says that when Men were cast on an Island, where there was no fresh Water; and they boiled Sea-Water; and catched the Vapour with Sponges, which they squeezed into another Boiler; and having passed thus, four or five Times from Boilers thro' Sponges, it became drinkable. This tedious way was used before the method of Disttiling was known, which was an Invention of the Arabs.
  • Johannes Gadesden [i.e.,] Johannes Anglicus, Anno 1516, says that Sea-Water may be sweetened four ways, viz. by filtrating thro' Sand: By clean Linnen laid over a Boiler, and squeesing the Moisture out, as from the Sponges: By Distillation: As alfo by thin Bowls made of white Virgin Wax, which 'tis said will free the Water from its Saltness, and from some part of its nauseous Bitter. But this is only a matter of curiosity, because but a very small Quantity can be thus prepared; and in order to make those waxen Bowls fit for farther Filtration, they must be cleansed from the Salt, by being washed in fresh Water.
  • About the Year 1675, William Walcot, Brother to Sir Thomas Walcot, obtained a Patent for making Sea-Water fresh: And the King, before the Grant of this Patent, had the curiosity to go and see Mr. Walcot do it, which was by distilling it in a very large Still; into the Still he put some Ingredient, which was to cure the distilled Water of any noxious Quality: But what it was, he kept a great secret. I suspect that the principal thing was only Distillation, because in all his printed Accounts of it, he purposely avoids the calling it a Still, but calls it a Machine or Engine, and Distilling he calls the working of the Machine, not Distilling.
  • The Reverend Dr. Colbatch... who some Years since desired me to attempt, to make Sea-Water wholesome, informs me that he had good Reason to believe that the Ingredient which Mr. Walcot put into Sea-Water, in order to make it wholesome, was some Preparation of Antimony by Fire.
  • In the Year 1683 Mr. Fitz-gerald, a near Relation of the Famous Robert Boyle Esq; having upon Mr. Boyle's encouragement made a Discovery of a new easy and practicable way of making salt Water fresh... Mr. Walcot asserted before the House of Commons, that Mr. Fitz-gerald's Water was rough, harsh, fiery, corroding and tormenting the Body when constantly drank of. This I suspect was the true Reason why both their Methods of preparing fresh Sea-Water were disused...
  • Mr. Walcot says of his Water, that it was smooth, soft, cooling, and would not decay or putrify in many Years, no not in seven Years... But by its continuing so long in an unputrified State, I suspect there was Spirit of Salt in it, that came over in Distillation: For tho' distiiled common Water is known to keep longer without putrifying, than undistilled Water by reason of its greater purity; yet I found some of the good distiiled Sea-Water to putrify in some time after Distillation, but that which had in it Spirit of Salt never putrified.
  • I find that a small Degree of Putrefaction in Water, kills Fish; but if, in order to prevent that Putrefacton, a few Drops of Spirit or Oil of Vitriol be dropped into the Water, then the Fish will live many Days in that Water.

A Description of Ventilators (1743)

: Whereby Great Quantities of Fresh Air May with Ease be conveyed into Mines, Goals, Hospitals, Work Houses, and Ships, In Exchange for their Noxious Air. An Account also of their Great Usefulness in many other Respects: As in Preserving all sorts of Grain Dry, Sweet, and free from being Destroyed by Weevels, both in Graineries and Ships: And in Preserving many other Sorts of Goods. As also in drying Corn, Malt, Hops, Gun-Powder, &c. and for many other useful Purposes. Which was read before the Royal Society in May 1741. A source.


  • There is no doubt but it will fully answer your Lordships tender Care and Concern for the Welfare of Navigators, as it will contribute much to their Health, by supplying them, in exchange for a very noxious, with Plenty of fresh Air, that genuine Cordial of Life: For that wonderful Fluid the Air, which, by infinite Combinations with natural Bodies, produces surprizing Effects, as it is on the one Hand when pure, the chief Nourisher and Preserver of the Life of Animals and Vegetables; so, when foul and putrid, it is the great Principle of their Destruction.
  • As Sea-farers, that Valuable and Useful Part of Mankind, have many Hardships and Difficulties to contend with, so it is of great Importance to obviate as many of them as possible: And as the noxious Air in Ships has hitherto been one of their greatest Grievances, by making sick and destroying multitudes of them; so the finding a Means to prevent this great Evil, is of vastly more Consequence to Navigation, than the Discovery of the Longitude; as being a Means of saving innumerable more Lives...
  • [It] is evident, not only from considering the Effects of the Engine, which exchanges great Quantities of bad, for good Air; but also from the Event it having been found very salutary by the Swedes who have made the Trial.
  • 'Tis a good Symptom that we are got upon a right Scent, when it leads not only to the Thing first sought for; but also to many other useful Discoveries, as we see this does.
  • We have here an Instance, that the Study of Natural Philosophy is not a meer trifling Amusement... For it not only delights the Mind, and gives it the most agreeable Entertainment, in seeing in every thing the Wisdom of the great Architect of Nature: But it is also the most likely Means, to make the Gift of kind Providence, this natural World, the more beneficial to us, by teaching us how, both to avoid what is Hurtful, and to pursue what is most Useful and Beneficial to us.

The Preface

  • In the Year 1740, I wrote to Dr. Martin Physician to Lord Cathcart, General of the Forces which lay imbarked at Spithead, for an Expedition in America, to propose (besides the usual sprinkling between Decks with Vinegar) the hanging up very many Cloths dipped in Vinegar, in proper Places between Decks, in order to make the Air more wholesome: And in case an infectious Distemper should be in any Ship, to cure the Infection with the Fumes of burning Brimstone.
  • [I]t occurred to me the March following, that large Ventilators would be very serviceable, in making the Air in Ships more wholesome; this I was so fully satisfied of, that I immediately drew up an Account of it; several Copies of wbich were communicated, both by my self and others, to many Persons of Distinction, and Members of the Royal Society: Before whom I laid a large Account of it, which was read in their Presence the May following...
  • November the sixth following, viz. in the Year 1741 Martin Triewald, Captain of Mechanicks and Military Architect to the King of Sweden, and Fellow of the Royal Society at London, in a Letter to Cromwell Mortimer M.D. and Secretary of the Royal Society, says, that "this Spring he had invented a Machine, for the Use of his Majesty's Men of War, which went to block up Petersburgh, in order to draw out the bad Air from under their Decks, the least of which does exhaust 36172 cubick Feet of Air in an Hour,"...
  • It were a very extraordinary Circumstance that two Persons at so great a Distance from each other, without getting a Hint of it one from the other, should happen to hit on inventing a like very useful Engine.
  • For this Engine [Mårten Triewald] had a Privilege for Life granted him by the King and Senate of Sweden, dated the 20th October 1741...
  • A Translation of which ingenious Treatise, was communicated to me by Dr. Mortimer; in which he says, "In Hospitals and Barracks for the Sick, this Machine is placed in the Garret, from whence two or three Pipes go down, some Inches thro' the Ceiling, into each Room where the Sick lie; and thus draw out all the unwholesome Air and Stench, which does more harm than any Physick can repair. And at the same time, has this accidental Benefit, That those who begin to mend, may give themselves a proper Exercise, in working the Machine: Only they ought to take care to keep all the Garret-Windows open, while the Machine is a going. In Men of War and Hospital-Ships, this Machine is placed on the upper Deck, directly over the great other Hatch: And then the Pipe, which goes down between the Decks, draws out the unwholesome Air; which is instantly supplied by fresh.
  • This Treatise, he says, was read before the Royal Academy of Sweden the third day of April 1742. ...This was eleven Months after mine was laid before the Royal Society.
  • And in his Letter to Baron Wasenberg, Envoy from the King of Sweden, dated the 22d of April 1743... he says, "that every Swedish Man of War, and Hospital Ship, was last Year furnished with one of my Engines; which had not been done, in case so they had not experienced the Benefit of the same, the Campaign so before that." So that a Trial was made with these Ventilators in the Year 1741, which proved a very sickly Summer in the Swedish Fleet, except only in the Ship or Ships, which were refreshed by Ventilators: A strong Instance of their great Usefulness; which induced the Swedes to put them into every Man of War and Hospital-Ship, the rear following.
  • And Mr. Triewald further says, that in the Summer of the Year 1742, be bad sent one of his Engines, calculated for a Sixty Gun Man of War, to France; which being approved of by the Royal Academy of Sciences at Paris, the King of France has ordered all the Men of War to be furnished with the like Ventilators.
  • Being informed, while this Book was printing, that it was said that Nathaniel Henshaw M.D. F.R.S. had long since made a like Proposal, for sweetning the Air of Ships, in a Treatise called Aëro-Chalinos, or a Register for the Air, printed in the Year 1677... In which Book is the following Proposal, viz. In order to have the Benefit of Change of Air, to another Country or Climate, almost at any Season, and that without going out of the House; he would have a Room, which he calls an Air-Chamber, to be built... Air-tight every where; with a very large Pair of Organ-Bellows to be placed in the Room; to or from which, Air is to be conveyed through the Wall, by a Copper Pipe; with Valves to open inward or outward as Occasion shall require. With these Bellows, the Air in the Room is either to be condensed and made heavier, by forcing Air in, or lighter, by conveying Air out of the Room.
  • He proposes by this means to cure intermitting Fevers, by having the Air in the Room rarefied in the cold Fit, and condensed in the hot Fit; during the whole time of which, the Patient is to continue therein: And recommends the use of it, among other Distempers, to cure the Stone and the Pox.
  • He proposes also to prevent Sea-Sickness thereby, by having a Man thus shut up in a close Cabin in a compressed Air: This, I suppose, has led some to say, that this and my Proposal are the same. But bow wide is their Difference! My Ventilators are intended to promote a free Perspiration and Breathing, by conveying great Quantities of fresh Air into Ships, in exchange for very bad Air. On the contrary, Dr. Henshaw's Conetrivance would make a good Air, by confining it, very bad, and thereby retard Perspiration, and incommode the Breathing, and so cause, instead of preventing, Sickness... Besides, the Make of my Ventilators is very different from that of Organ-Bellows.
  • As these Ventilators are like to prove of great Benefit to Mankind, in many other Respects than are here mentioned, or can as yet be thought of; so it will be of great use, if those who shall have made farther Improvements, will... communicate them; as also an Account of the Difficulties or Success they have met with in putting the Things here proposed in execution.

An Account of Some Experiments and Observations on Tar-Water (1745)

: Wherein is shown the Quantity of Tar that is therein. And Also A Method proposed, both to abate that Quantity considerably, and to ascertain the Strength of the Tar-Water. Which was read before the Royal Society.
  • As the celebrated Tar-water, recommended by the worthy and learned Bishop Berkeley, is said to be taken with great Benefit by some, and Detriment by others; I thought it might probably be of use to inquire whether any, or what Quantity of Tar, there was in Tar-water, made with different kinds of Tar, different Degrees of stirring, and in different Ways of making it. A short Account of which I shall give, without interesting myself, either in Favour or Disfavour of a Medicine that is under the Inspection of the proper Judges, as well as of all the rest of the World.
  • Upon Inquiry from knowing Persons, I find that Norway or Swedish Tar, which is dark, thick and clear... is accounted the best for the general Uses... But that the Tar which is made of the Tops of Fir-Trees... having lain long dead... after having either fallen... or being killed by the draining off their Turpentine Sap... (These Tops are commonly called Light-wood, the poorer People making use of them instead of Candles:) This Tar being burned in a very strong Fire of such dry Wood, is of a very caustick, corroding Nature, so as to be hurtful to Ropes, &c. for which reason it is not used in the Royal Navy. But the American Tar, which is made of green Fir-Trees, with a less degree of Fire, is esteemed good, and is called green Tar...
  • Having procured some Norway or Swedish Tar which was thirty Years old... I, according to the Bishop's Prescription, made Tar-water in the proportion of a Gallon of Water to a Quart of Tar, stirring it four Minutes: I then took a Pint of this Tar-water, and evaporated it away in a Florence Flask, cut to a wide Orifice... and weighed.
  • When Tar-waters of different Degrees of Strength were put into Florence Flasks, with other inverted Flasks fixed on them, and all were placed in the same Vessel of hot Water; on breaking the upper Flasks, the volatile acid Spirit could very sensibly be tasted, especially that of the stronger Tar-water; which shows that these Waters are impregnated therewith: and which when distilled from Turpentine, Dr. Boerhaave in his Chemistry says, is the best vegetable Acid that is known.
  • This Acid in Tar-water will curdle Milk; yet Turpentine-water will not... which shows that Tar is considerably acidulated, by the action of Fire in making.
  • We have seen in the Course of these Experiments, the Quantity of Tar that there is in Tar-Water; and the great Difference of that Quantity, made with different kinds of Tar, and different Degrees of Stirring. Now, since, notwithstanding these Quantities of Tar, and the additional more subtile volatile Oil, which flies off in Evaporation, it has yet undoubtedly proved an efficacious Remedy in many Cases and Instances; it may hence be reasonably concluded, that the Medicinal Virtue of the Water does not reside solely in the Acid, but partly also in the unctuous oily Parts, which are so temper'd by the Acid, as in some Cases to prevent their heating too much.
  • But whereas in some Cases, it is observed by Physicians to be too inflammatory, it is probable, that heating Quality, may in some Degree be abated, by making Tar-Water with the Strainer... without Stirring; thereby to divest the Water of a good Quantity of its grosser, tarrish Particles, and yet retain whatever Powers it may have to do good.
  • It is hoped, that the Light given by these Researches, may be of use in skilful Hands, for regulating and adapting the due Proportions of the acid, and the oily Principles, to different Cases and Constitutions. This is the proper Province of the Physician, which I am no ways qualified to meddle in.

A Friendly Admonition to the Drinkers of Gin, Brandy, and Other Distilled Spirituous Liquors (1751)

With an Humble Representation of the Necessity of restraining a Vice so destructive of the Industry, Morals, Health, and Lives of the People. To which are Added, In an Appendix, Directions by a very Eminent Physician, to such as may be desirous to break off that odious and fatal Habit of drinking Drams. A source.
  • Man, not contented with the Liquors, which his bountiful Creator intending for his Comfort, has wisely tempered with such a due Proportion of Strength, as would (if taken in Moderation,) make his Heart glad, has unhappily found Means to extract, from what God provided for his Refreshment, a most intoxicating and baneful Spirit, to which, in a great measure, is owing the remarkable Increase of Drunkenness of late Years; which Vice reigns to a most enormous Degree, among the habitual Drinkers of Gin, Brandy, and other Distilled Liquors; which are found to be most pernicious and destructive. For at the same shat they coagulate and thicken the Blood, they also contract and narrow the Blood-Vesels; which has, in fact, been found to be true, by Experiments I have purposely made with Brandy, on the Blood and Blood-Vesels of Animals.
  • Whence we may evidently see the Reason why those Liquors do so frequently cause those Obstructions and Stoppages in the Liver; which occasion the Jaundice, Dropsy, and many other fatal Diseases.
  • It is in like manner also that they destroy and burn up the Lungs. Hence also it is, that by frequently contracting and shrivelling, and then soon after relaxing, they weaken and wear out the Substance and Coats of the Stomach, on which they more immediately prey, every time they are drank.
  • Hence likewise it is, that these spirituous Liquors rarely fail to destroy the Appetite and Digestion of those, who habituate themselves to them; for by drying up, and spoiling the Nerves, they make them insensible; they destroy also many of the very fine Blood Vessels, especially where their Fibres are most tender, as in the Brain; by which means, the Memory and intellectual Faculties are ruined: Nay, by inflaming the Blood, and disordering the Blood-Vessels and Nerves, they vitiate and deprave the Natural Temper.

Quotes about Hales

  • Could anything increase the pleasure I have in a literary intercourse with you, it would be to find that it answered your end in promoting the publick good. ... It does honour to those noble and other worthy personages that join you in acts of such extensive humanity as the introduction of ventilators into hospitals, prisons, ships of war, and transports, &c. as they must necessarily render the miseries of the first more supportable, and the close and constant confinement of the others less prejudicial and fatal to their health and life. It is to be lamented, that they are not more generally made use of... Those of your invention which I had were of singular service to us; they kept the inside of the ship cool, sweet, dry, and healthy: The number of slaves which I buried was very inconsiderable, and not one white man of our crew (which was thirty four) during a voyage of fifteen months; an instance very uncommon. The 340 negroes were very sensible of the benefits of a constant ventilation, and were always displeased when it was omitted. Even the exercise had an advantage not to be despised among people so much confined. ...Could I but see the immoderate use of spirituous liquors less general, and the benefit of ventilators more known and experienced, I might then hope to see mankind better and happier.
    • A Letter from Capt. Ellis, on his late Arrival from a Guinea Voyage, to the Rev. Dr. Hales The Gentleman's Magazine (March 1754) Vol. 24, pp. 114-115.
  • The following Character of the late Dr. Hales, may he relied upon in every particular, and it is to he regretted that we have not more particulars concerning his useful Life from the same hand. On Sunday the 4th instant [1761], died, at his parsonage-house at Tedington, universally lamented, in the 83rd year of his age, the Rev. Dr. Stephen Hales, F.R.S., member of the royal academy of sciences at Paris and clerk of the closet to her Royal Highness the Princess Dowager of Wales. If any man might ever be said to have devoted his whole life to the public, to all mankind, it was Dr. Hales. He possessed a native innocence and simplicity of manners, which the characters of other men, and the customs of the world, could never alter; and though he often met with many unworthy objects of his kind and charitable offices, yet they never once lessened his natural and unwearied disposition of doing good and relieving distress. His temper, as well as the powers of his understanding, were happily fitted for the improvement of natural philosophy, possessing, as he did, in an uncommon degree, that industry and patient thinking, which Sir Isaac Newton used modestly to declare, was his own only secret by which he was enabled so fortunately to trace the wonderful analysis of nature. Dr. Hales began his inquiries into natural knowledge very early in life, and he continued it uniformly as his darling amusement, being engaged in experiments until within a few weeks of his death. His industry had this farther excellence, that it was always pointed at the general good of his fellow creatures, agreeable to the almost unlimited benevolence of his heart; and being animated with the success of some of his more useful discoveries, his knowledge appeared to everybody near him to feed his mind with a nourishment which gave him, in the decline of his life, and even in its last stages that vigor and serenity of understanding, and clearness of ideas, which so few possess, even [in] the flower of manhood; and which he used often to say, he valued as the most perfect of human pleasures. ...There are two things in his character, which particularly distinguish him from almost every other man; the first was, that his mind was so habitually bent on acquiring knowledge, that, having what he thought an abundant income, he was solicitous to avoid any farther preferment in the church, lest his time and attention might thereby be diverted from his other favorite and useful occupations.
    The other feature of his character was no less singular: He could look even upon wicked men, and those who did him unkind offices without any emotion of particular indignation; not for want of discernment or sensibility; but he used to consider them only as those experiments which, upon trial, he found could never be applied to any useful purpose, and which he therefore calmly and dispationately laid aside.
    • Sylvanus Urban, "Character of the Rev. Dr. Hales" The Gentleman's Magazine (January 1761) Vol. 31, p. 32.
  • Green Teddington's serene retreat,
    For Philosophic studies meet,
    Where the good Pastor, Stephen Hales
    Weigh'd moisture in a pair of scales,
    To ling'ring death put mares and dogs,
    And stripp'd the skin from living frogs
    (Nature he loved, her works intent
    To search, and sometimes, to torment!)

The Biography OF Stephen Hales, D.D., F. R. S. (June, 1904)

by Percy M. Dawson, M. D. From The Johns Hopkins Hospital Bulletin, Vol. XV, No. 159, June, 1904. A source.
  • [T]he first important conception to be grasped by the student is that of the blood pressure, and the first experiment is designed to demonstrate its existence and to estimate its amount. ...It consists in connecting the femoral artery of a dog to a long glass tube. Into this tube the blood mounts up and up to a height of five or six feet and then oscillates up or down with each contraction or relaxation of the heart. Such a tube... is called... the "Hales manometer" after its inventor... Dr. Hales.
  • During his residence in the college, a period of about twelve years (1696-1708 or 1709), he applied himself with great zeal to the study of natural and experimental philosophy.
  • In William Stukeley... who came in 1704 to live in Corpus Christi College, Hales seems to have found a very congenial companion, though Stukeley was the younger by ten years. ...The two friends also studied anatomy together, dissecting frogs, dogs and other animals; while Hales devised an ingenious method of obtaining a preparation of the lungs in lead. They moreover studied chemistry and "repeated many of Mr. Boyle’s experiments" and prepared various substances, "some of use, some of curiosity."
  • Hales and Stukeley... were also witnesses of the chemical operations which Vigani was accustomed to perform in a room in Trinity College... formerly... the laboratory of Sir Isaac Newton.
  • Hales was also a student of astronomy and constructed a brass machine for demonstrating the movements of the planets, and of this Stukeley made a sketch.
  • In 1719 he reported before the Royal Society some experiments which he had lately made on the effect of the sun’s warmth in raising the sap in trees. ...[T]he Society... requested him to continue his research. [Peter Collinson ] writes, "...Hales complied with great pleasure, and on the 14th of June, 1725, he exhibited a treatise in which he gave an account of his progress." At the request of the Society this treatise was published an appeared in 1727 under the following title: "Vegetable Staticks..."
  • The "Vegetable Staticks" was so well received that a second edition was published in 1731.
  • [I]n 1733 he published his second famous work, entitled "Statical Essays: containing Haemostaticks, or an Account of some Hy- draulick and Hydrostatical Experiments made on the Blood and Blood-Vessels of Animals..."
  • These two books were again edited under the title, "Statical Essays, Vols. I & II."
  • Through the "Statical Essays" Hales came to have an international reputation... [being] translated into French... German and Italian...
  • [T]he essential and distinguishing characteristics of these essays... would be that the work... is quantitative. ...Qualitative results were never sufficient; Hales must needs weigh and measure everything, and every phenomenon must be expressed numerically so as to serve as the basis of calculations and thus lead to new discoveries.
  • Hales’ life fell very early in the history of scientific chemistry, in that period when experimentation, though often suggestive, is usually indefinite and always incomplete.
  • Hales made a careful study of gases, or, as he called them, "air."
  • To him air was an element which entered into the composition of a surprising number of substances, and so he studied the generation and absorption of "air" during distillation, fermentation and many other chemical processes.
  • In his experiments he must have prepared hydrogen, oxygen, hydrochloric acid, carbon dioxide and ammonia, and though they were all "air" to him, he introduced some important improvements in the way of chemical apparatus and manipulations, and was perhaps the first chemist to employ quantitative methods.
    • Footnote: See Herman Kopp: Geschichte der Chemie. Braunschweig, 1845.
  • Sachs... writes that in the revival of plant physiology which took place in the eighteenth century, the work of Hales was the most original and most important contribution.
  • It was in honor of Hales that John Ellis, the "bright star in Natural History," as Linnaeus has called him, named a newly discovered genus of plants Halesia.
  • In 1739 he published an octavo volume entitled: "Philosophical experiments: containing useful and necessary instructions for such as undertake long Voyages at Sea..." This work, which contained so many useful instructions for voyagers, was dedicated to the Lords of the Admiralty.
  • In [1739] he reported to the Royal Society an account of some "further experiments towards the discovery of a medicine for dissolving the stone in the kidneys and bladder, and preserving meat in long voyages," and it was for this that he received the [Copley Medal]. In the following year he published an account of some experiments and observations on Miss Stephens’ medicines for dissolving stone, in which their dissolving power was inquired into and demonstrated.
  • The contributions of Hales to the "Philosophical Transactions" were numerous and dealt with a great variety of topics. ...the following [9 not shown here] may be enumerated... Whenever these papers seemed to him to be of value to the public or to deal with topics of general interest, he would publish a popularized version in the Gentleman's Magazine. But besides these abstracts this magazine contains numerous articles from his pen, of which the following [5 not shown here] are the more important...
  • The year 1741 is ever memorable in the history of Hygiene, for it was in this year that three persons... conceived the idea of constructing ventilators. These... were [Samuel] Sutton, a coffee-house keeper in Aldersgate Street; Martin Triewald, captain of mechanics to the King of Sweden, and the Rev. Dr. Hales.
  • The methods devised by Hales and Triewald seem to have been identical, and the history of their invention is told by Hales in his book on ventilators published in 1743.
  • For this [ventilator] invention Triewald was granted a privilege for life by the King and Senate of Sweden. He then wrote a "deduction" on the usefulness of ventilators... distributed among... naval officers. This "deduction" was read before the Royal Society in 1742. In it Triewald recommends the use of ventilators "in Hospitals and Barracks for the sick, Men-of-War and Hospital Ships."
  • The Hales ventilators were nothing more than ingeniously contrived bellows which sucked the foul air from the rooms or spaces to be ventilated and blew it out of doors. When large, these bellows were worked by means of a wind-mill; when small, by hand.
  • Not content with playing the part of a mere inventor, Hales added to that role... philanthropist, for seeing that it would be of great benefit to humanity, he wrote constantly on the subject and used what influence he had to obtain the introduction of his ventilators. Success crowned his efforts. In a few years his ventilators had been put not only into Newgate and the Savoy prison, but also into the Winchester Gaol, the Durham County Gaol, then the Gaols of Shrewsbury, Northampton and Maidstone. The results were remarkable. During the first four months after their introduction into Newgate, the death rate was reduced by more than fifty per cent, while in the Savoy prison the rate fell from fifty or a hundred per annum to one or two per annum. Equally gratifying were the results at the smallpox hospitals. the mortality was soon reduced to two-thirds of what it had formerly been.
  • The Gentleman's Magazine... contains... An Account of several methods to preserve Corn well by Ventilation: June, 1746, XVI... accompanied with plates [it] contained a careful and minute description of the construction of granaries, with calculations regarding the size of the ventilator and the amount of air required for drying a certain amount of a given kind of grain in layers of such a depth in granaries of such a size and so forth... showing his painstaking accuracy and his detailed knowledge of the subject.
  • The ventilator... invented by [Samuel] Sutton... was "of another construction," being designed "to draw off the foul air on board ships by means of the cook-room fire." Sutton did not fully recognize the importance of his idea, so that it would have been forgotten had it not been for Dr. Mead, who brought it to the attention of the Royal Society.
  • [T]he Gentlemans Magazine says, "...Dr. Hales['s] ventilators came more easily into use for many purposes of the greatest importance... particularly for keeping corn sweet..." ...Duhamel du Monceau the suggestion of Hales, equipped one of the [French] public granaries with a wind-mill and ventilators to draw up air through the grain.
    It was probably through Duhamel's influence that Hales persuaded Louis XV to introduce his system of ventilating into the French prisons in which British soldiers were confined.
  • Dr. Holmes has made us all familiar with the subject of Bishop Berkeley’s "Tar Water." ...Hales shows a praiseworthy caution. He does not deny its efficacy, but he does not advocate its use. ...In the book ["An Account of some Experiments and Observations on Tar-Water..."]... he confines himself entirely to the chemistry and preparation of tar water.
    • Holmes/Berkeley reference: Oliver Wendell Holmes Sr., "Homœpathy and its Kindred Illusions" Medical Essays 1842-1882 (1896) p. 11.
  • Among the subjects which Hales regarded as of great importance was the liquor question. ...[In "Distilled Spirituous Liquors the Bane of the Nation"] he tries to arouse the interest of the landed gentry and the farming population on the ground that dram drinking decreases the appetite and lowers the demand for food. Then... he declares that... the country loses £600,000 per annum owing to the distilleries in London alone.
  • Under his supervision the water supply of the [Teddington] parish was greatly improved...
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