an investigation into
Dr Neil Arnott. MD. FRS

      Researched, prepared and
      written by F J Ferris for the
      Heritage Group of the CIBSE
      November  2005

                         with acknowledgements to,

The Royal Society,

                     Central Library Bristol,
                     The Times Newspaper,
                     Oxford Dictionary of National Biography,
Wikipedia  Encyclopedia,
                     1851 Great Exhibition List of Exhibits,
British Library Patents Section
                        for their assistance and information.

The following website article about Dr Neil Arnott is an ongoing Heritage Group project. More webpages will be added as further information is discovered.

Dr Neil Arnott 1788 - 1874 was a man of many talents including physician, public health reformer, inventor, patentee, lecturer and author. He was elected a Fellow of The Royal Society on 5th January 1838 with the following citation "Neil Arnott MD of Bedford Square a Gentleman well aquainted with the various branches of science being desirous of becoming a fellow of The Royal Society. We the undersigned of our personal knowledge recommend him a deserving of that honour and as likely to prove a valuable and useful member"

He was born in Arbroath Forfarshire Scotland on the 15th May 1788. Educated by his mother at the parish school of Lunan, then at Aberdeen grammar school. In 1806 he graduated with an MD from Marischal College Aberdeen. He received his Diploma of the Royal College of Surgeons in 1813 and was awarded his MD the following year.

He expressed his concern about what he called the four necessaties of life, Air, Warmth, Aliment and Exercise. All these factors must have created his interest in heating and ventilating which started with his involvement in matters related to public health and the need for improved ventilation in buildings. This led in 1838 to his publishing of the book titled "Warming and Ventilating" which explained the principles used in the Arnott slow combustion stove. The Royal Society awarded him the Rumford medal on 30th November 1854. The medal citation read "For the successful construction of the smokeless firegrate lately introduced by him and for other valuable improvements in the application of heat to warming and ventilating of apartments". In 1855 he published another book on the smokeless fireplace.

During the 1840's and 1850's Arnott is living at 38 Bedford Place in London. By 1861 he marries for the first time late in life to Marianne, and they move to a new residence at
2 Cumberland Terrace, Marylebone in London.

It appears that the Arnott stove was first manufactured following the publishing of his 1838 book."Warming and Ventilating", and although it states that the stove was Patented this was not the case. Letters to The Times newspaper called the absence of a Patent  "a serious misfortune to the public".
The fact that
Arnott did not patent the invention of his stove allowed other people to copy the design principle, and many different firms then manufactured the Arnott Stove making variations to his original design which subsequently led to problems with the stoves performance, reliability and safety.

See The Times newspaper articles.   In every street in London stoves were offered for sale bearing Arnotts name, of which not 1 in 50 was made in accordance with the design principles described by Arnott. So, imperfect stoves together with their incorrect use and firing method brought the invention into disrepute.

Warm air stoves based upon Arnott's design came in for much criticism during the late 1830's. The number of stoves being installed increased dramatically, and many stove explosions occurred during this time, generally attributed to the different designs of stoves (carrying the Arnott name) that were being sold and erected.  Letters were written to The Times newspaper, seeking advice on the management of the stove as stove owners became increasingly concerned about their safety. 

The following are a selection of those letters.



Sir, - As Arnott’s stoves are daily coming more into use, you will much oblige me if you will allow some of your numerous readers to favour me (and others who may need it) with their experience in the management of these stoves. To oblige my wife, I was induced last Tuesday, to have one of them brought from London and fixed in my dining room. I took the precaution to have the regulator enclosed and locked up; and that the stove might have a fair trail, I had the stove coal sent down from the house of the stove maker, and two of his men to fix it ; and that there might be no mistake, I determined, for the first week, to put the coals on myself, which I did at 9 o’clock at night, and 9 in the morning. On Thursday morning I first observed that an explosion of gas blew out of the regulating valve underneath the chair I was sitting on, carrying with it sparks of fire, and this continued at intervals till Sunday morning when on opening the door to look at the fire, the gas rushed out so far into the room, that it blew back the breakfast cloth. A short time after it again rushed out of the valve with such violence as to occasion great alarm to the family in the room. About an hour after that (10 o’clock) the butler was alone in the room, when a violent explosion took place, lifting the stove off the ground, breaking a carved marble mantelpiece into three pieces, the centre falling upon the stove, and a cloud of smoke, or gas rising up before the looking glass (a very large one), so as to almost hide it from view.

Some persons will perhaps say that improper coal has been used. To this I reply that I have since had it tested, and it is proved to be quite correct – the Welsh stone coal. There appears to be some difficulty in accounting for this (as I am informed) very unusual occurrence. I am desirous of getting rid of this very dangerous comfort, and returning to my old English fireside, but it is much wished by the young people to give this stove another trial. Can any of your experienced readers inform me how I may guard against such another disaster ?

                                        I am sir, your obedient servant

                                                      A COUNTRY GENTLEMAN
December 24 1839



Sir, - Whenever the air valve of this stove is shut, it is converted pro tempore into a retort, and the gas generated, having little (if any) current into the smoke flue, causes the explosions complained of by your correspondent. To remedy this, air should be constantly applied to the fire, so as to produce a continual current into the smoke-flue, and the door of the ash-pit (which feeds the fire with air) always opened a few minutes previous to every fresh supply of fuel.

                                                       I am sir, your obedient servant,

                                                                                                            W. S. I.
           December 26 1839


Sir,  - In your paper of the 25th November a letter appears signed “A Country Gentleman” on the subject of Dr Arnott’s stoves, and stating that an explosion had taken place in his house from having used Welsh stone coal.  I do not doubt the account of the explosion, or that the gentleman believes he used stone coal or anthracite. Still he must allow me to say he has been imposed upon; as I am confident it is not possible to generate gas of a character to be able to lift an Arnott stove off the ground by simply burning stone coal in that or any other stove.

In the belief that “the Country Gentleman” wishes only for a satisfactory explanation of a very dangerous and unpleasant consequence, I send you my address, inviting him to communicate with me when I doubt not, I can convince him of what I here state.

                                           I am Sir, your obedient servant,

December 26  1839


Sir, - An accident having occurred from the use of Dr Arnott’s stove, as attested by a “Country Gentleman” in the Times of the 25th November, I am induced to reply to his letter, with a view of affording him and the public at large some sort of protection against similar disasters. I should first caution the “Country Gentleman” against tampering with any engine that has already proved so far uncontrollable as to have destroyed a marble mantel-piece, and which may in its next freak fracture the leaking glass and other movables. The “Country Gentleman” is misinformed as to these explosions being unusual or unaccountable; they are likely to recur as often as the imperfect stove is set in use, and are accounted for as follows:-

Most people know that a fish kettle, having a lid to fit nearly air tight, and requiring a certain force to remove it, would in a few seconds, after the water contained had reached boiling heat, collapse and in proportion to the tightness of the cover, so would be the force of the explosion of steam ; the non-explosion of such vessels is owing to the sagacity of the tinman, that avoids making them airtight. This compliment cannot be paid to Dr Arnott’s stovemakers, although their task, like the tinman’s is only to avoid using their skill in making their work airtight.


Make a box of cast or sheet iron to contain a furnace of firestone, the outer case to have an airtight door, through which to supply the coal when opened ; below is required the ash-door, also to shut airtight. The air valve must shut airtight, and be held so by the pressure of a thermometric regulator kept in force within the stove. The stove-pipe fitted on airtight. The stove if set in a large chimney, stopped in the bottom quite airtight, may be made to explode as follows:-

Light the fire with wood, on account of the abundance of gas it will emit. Use Welsh coal, producing the highest degree of heat. Open the ash-door, that the coal and fire brick may become red hot.  When highly heated put on fresh coal ; shut the doors – the valve will shut itself  - and thus you have a first class gas retort, warming the room at the same time with the utmost economy – indeed without combustion, as no air enters to combine with the heated carbon. In time the stove and chimney become filled with hydrogen gas ; as the heat falls in the furnace the valve opens,  a little undulation in the pressure of the atmosphere or the opening of a door will force air through the valve, which being mixed with the hydrogen gas in the stove, on coming in contact with the red hot coal, produces an explosion, the power of which is proportionate to the quantity of gas accumulated and the method taken to confine it. The house might be thrown down by stopping the chimney-pot also airtight after the full heat is obtained. Dr Arnott’s stoves with doors ground together, and a regulator receiving the internal heat, are liable to explode from the above causes, that is the exclusion of air by regulators acting imperfectly.

As several accidents have occurred from the use of airtight stoves, I presume this information may deserve a place in The Times.                                                 

                                                  I am Sir, your obedient humble servant,

                                                                                                   A PNEUMATICIAN

December 26  1839


Sir, That Dr Arnott did not take out a Patent for his invention has proved a serious misfortune to the public. In every street of this metropolis stoves are offered for sale bearing the Doctor’s name, of which not 1 in 50 is made in accordance with the principles he has laid down. Hence imperfect stoves as well as improper management, bring unmerited disgrace upon the invention. From the description given by “Country Gentleman” of the stove, either that was imperfect or he was doing what should not be done – the ash-pit door probably open. The chief thing is to let it alone, for a good stove when regulated want little more than for the servant once in the 24 hours to put on a little fuel and take away the ashes.

Respecting the letters which you have inserted, I beg leave to make a few observations, having had some practical experience “W S I” is not right, for in a well-regulated stove the valve will sometimes be closed; but when the stove cools, and the valve is reopened,  its action is so gentle that combustion does not go on at a rate sufficient to produce explosive gas in any dangerous quantity. He is decidedly wrong as to the ash-pit door – that should never be opened except when necessary for the removal of the ashes.

With ANOPAX I cannot agree, never having met with anthracite coal so pure but that, by leaving open the ash-pit door, thereby most rapidly generating the gas, the stove becoming a furnace and retort (mark Sir, those who have Dr Arnott’s stoves are strictly enjoined not to do this), I could effect what the doctor in his book terms a “semi-explosion” – that is a jet of blue flame from the feeding door the moment it is opened, and I know of a stove which blew up at the makers, the ash-pit door having been left open.

The stove of Dr Arnott, when properly constructed, and regulated, is a great comfort, as well as a great saving, both in fuel and attendance.

                                                                                                                        R R.

Threadneedle Street   December 26 1839



Sir, - My object in addressing a letter to you for insertion in your valuable journal on the subject of what are called Dr Arnott’s stoves was to accomplish precisely what has been the result – to elicit information for myself, and to further the doctors well known and approved philanthropy. I should have addressed a private letter to Dr Arnott for information, but considered the value of his time, did not think myself entitled. If on public grounds you, Sir, consider this further explanation worth insertion, I feel it due to Dr Arnott thus to communicate, he having addressed you on the subject, as appears in this days journal being still anxious to have a stove on his principle. After I sent you my first letter I requested the maker of the stove to come down, hoping that he might be able to discover the cause of the accident.

He came and brought for my satisfaction as he stated, and not from “any want of confidence in his own judgement” a rival stove maker, to ascertain if there was any fault in the construction of the stove. They remained with me nearly two hours and determined that the fault rested entirely in the chimney, and that the explosion mustand preventing the gas escaping ; or from the size of the chimney, the very wet weather having so chilled the chimney that the gas lingered at the bottom. The mantelpiece not having been mended, have occurred from the wind blowing down, there was now a current of air in the chimney, and being a very fine day both the gentlemen thought the circumstance would not occur again, and therefore put fuel on the fire, and it seemed to act very well while they were here; but in order to makeaperture out of the stove, and that there should be 50 feet of iron pipe, reaching from the sure everything was secure, they advised that the fireplace should be entirely bricked up and contracted to the size of the stove to the top of the chimney, which if done the maker agreed, should any further accident occur, he would make good all the damage.

They then left me between 2 and 3 o’clock, and we were much delighted in the prospect of being able to keep Dr Arnott’s stove. Everything appeared to go on well, although I am not aware that anyone particularly noticed it; but at before a quarter to 5 a most tremendous explosion took place, shaking the house, and bringing together every inmate to ascertain the extent of the damage. The stove had burst, driving up the inner case, and scattering the plaster of Paris (with which it had been fixed ) about the room; lifting also the loose top, which had again struck the mantelpiece remaining, and breaking it, bursting also the whole of the setting of the pipe from the stove. I am satisfied that this time the explosion took place in the stove, and I am inclined to think it was so before, and that the stove being lifted off the ground, struck and broke the mantelpiece, and that it was not broken from the force of gas from within the chimney. As soon as the first explosion took place, and before the stove-maker came down, I wrote to the coal-merchant for the names of some persons who were using the same coal (he had sent me) in Dr Arnott’s stoves. He sent me eight names of persons residing as follows:- “Whitehall Place, Upper Gloucester Place, Hereford Street, Suffolk Place, Notting Hill, Kings Road, Goldsmith Street and Hanover Square.” This I take for granted is a certificate that the coal was the proper anthracite coal.

Dr Arnott in his letter is silent with regard to the chimney. If the Doctors stove is not affected by a large chimney, I should be glad to know in what it differs from the stove I have had. This I am quite satisfied of, that it is necessary that those who use them should do so with care and caution. I am pleased to hear that the doctor is about to republish his work, which I have endeavoured to procure, but without success.

                                       I am Sir, your obedient servant,

                                                                                 A COUNTRY GENTLEMAN

January 1st 1840



Sir, - Allow me to thank you for the insertion of my two former letters in your valuable journal upon the subject of these stoves.

It has been the means of obtaining for me some very useful information, which I might not otherwise have been able to have received.

The stove-maker complains that I have “done him an injury by the publicity I have given to what has occurred in my house from his stove” (sold to me as one of Dr Arnott’s.) “He thinks that the whole facts and circumstances should be published by him, together with such observations as he may think necessary to make, and if he had my concurrence, he thinks it would be as well to do so with names of parties.”

I have written him that I can have no possible objection to any publicity which he may think it necessary to give in his own justification; and I am satisfied that you, Sir, will afford him the opportunity, if he should think it does to his or not. As I have fully paid for my experience, I think I am entitled to give the public the benefit of it, exclusive of the damage to the mantelpiece, and the alarm occasioned to the inmates of the houses. I have paid “ for cartage twice, to and from the country, to take and bring away the stove, fixing stove in dining room, and taking down again (the latter performed by my own work people), including bricklayers work, men’s time, and expenses going to examine the stove (after the first explosion), repairing the stove after using, etc.” (bursting). As I have not in either of my former letters named any stove maker in particular, I cannot see how I can have done this gentleman any injury more than every other maker of what are called Dr Arnott’s stoves. That such stoves as I have had are highly dangerous and explosive under almost any management, I feel justified in reasserting, and I feel satisfied that the publication of my letters has done some public good, and very little private wrong.

But the stove-maker is not the only party who complains. Your correspondent “ANOPAX” in a private letter to me, says “he is much interested in the clear elucidation of the repeated accidents in my house, as much as on behalf of the public as his own private account, being a very extensive holder of anthracite coal property, and he feels confident that my coal merchant has either sent me an article not anthracite at all; or if so, in any part, it is mixed with other coal. He thinks my coal merchant may have been imposed upon himself; for since the newly created demand for anthracite, many unprincipled people have taken advantage, and put off all sorts of rubbish under that name.” I have given him the name of my coal merchant, and offered to send up some of the coal if desired. I have not since heard from ANOPAX and therefore hope that I have not done any private injury to this gentleman. That there are some persons that mix this article I can believe, and that the public should be very cautious whom they buy anthracite coal of; for since I wrote to you first, I have heard of a great many other explosions. That my coal is the real anthracite, and not mixed I am quite satisfied, from its having been tested by many others, as well as those interested in its condemnation as those who have long so used it.

My next correspondent is the philanthropic Dr Arnott, who “regrets that I did not mention in either of my published letters, that the stove in question was not one made, or managed, according to directions given in his book.” Upon receipt of this letter I lost no time in calling on the Doctor, and assuring him that I could not say that the stove was not one made or managed according to his directions, for I certainly never should have admitted such a dangerous and destructive instrument into my house unless I had fully believed that it was one made according to his direction; and I had taken great pains to inquire, and thought I had put myself into first-rate hands. The Doctor’s book I had never seen, although I had tried to get a copy.

I am now anxious to do an act of justice to the doctor, in stating that I find from him that my stove was not made or regulated according to his directions, and that if it had been, no accident such as has occurred could have happened, or that there would have been any occasion to have found fault with, or to have condemned my chimneys.

I think the doctor’s stoves will increase in popularity, notwithstanding these circumstances, am so satisfied am I that the fault was not in the chimneys, that I intend trying again. The doctor in a few days will publish his new treatise, giving an account of the stoves at the Custom-house, and make his plan appear so clear, that every stovemaker who chooses may make them; but to relieve the fears of the more timid part of the public, he will name a scientific person who will examine any stove that he may be requested, and certify whether it is made strictly according to Dr Arnott’s directions or not. Upon a future trial let the decision rest whether I have done the stovemaker injustice in guarding the public (without naming anyone), or whether I may not justly complain that I should have had such an instrument sent into my house without any caution or hint of danger, but informed in the first instance by the warehouseman that the village bricklayer might set it.

I feel quite unconscious of having done anyone a private injury by any publication that I have given to this transaction, and hope I have shown the public there is danger in buying what are falsely called Dr Arnott’s stoves.

I have paid dearly for my experience. If anyone feels disposed to profit by it, I shall not regret the expense I have been put to; but they as well as myself, will feel obliged to you Sir, for allowing the space you have so kindly done in your journal to elicit information on a subject which is so closely allied to our own fire-sides.

                                                 I am Sir your obedient servant

                                                                          A COUNTRY GENTLEMAN
January 15  1840

One firm who made the Arnott pattern stove was Frederick Edwards (Stove Maker to Queen Victoria) who exhibited their example of the Arnott stove (as shown below) at the 1851 Great Exhibition held at the Crystal Palace, London.

At the 1851 Great Exhibition, Arnott was appointed a Juror for the Civil Engineering, Architectural and Building Contrivences Section 7 under the chairmanship of Isambard Kingdom Brunel.

Dr Arnott's circular and oblong bronzed corrugated stoves for warming buildings. By the corrugation of the body of the stove, the heating surface becomes multiplied nearly three times and by means of the self regulating valve the admission of air to the fire is so regulated that it only needs replenishing with fuel once every 12 to 18 hours.

This stove is shown by a front elevation and a sectional plan view. The amount of heating surface is partly represented by the indented line in the plan view.

The stove needs to be lighted only once in the season, and to be supplied with fuel only once, or twice if desired, in twenty four hours, consumes its fuel as uniformly as an hour-glass lets fall its sand, and can be adjusted to burn permanently at any wished for rate. It also facilitates perfect ventilation.

It can be assumed that the Arnott stove was being installed in quantity during the 1830's and 1840's when it would have been in competition with the built-in type of warm air stoves made by G&J Haden and William Sylvester.  If it could be established that the Arnott slow combustion stove was first installed in the 1830's, and the letter to The Times newspaper in 1841 would seem to confirm this fact, then it becomes one of the first, if not the first, stand alone warm air stove to have been invented.  The corrugated outer surface of the stove which increased the heating surface area by a factor of 3 was an innovative design concept which appears to have been adopted in principle in the later designs and patent applications of similar stand alone stoves invented and patented by Sir Goldsworthy Gurney 1856, and John Grundy 1864.

The Arnott warm air stove continued its popularity into the second half of the 1800's and as late as 1882 at a smoke abatement exhibition held in London one of the exhibits on display was his well-known stove, which by then had been in existence for half a century.

From the following advertisement which appeared in the 1851 Great Exhibition List of Exhibits, it reads that 40 different sizes and patterns of stove were being marketted by Frederick Edwards. Endevouring to obtain a copy of their catalogue showing these stoves has become  another research project for the Heritage Group.

Chimney Valves for Ventilating Rooms.
(as shown below)

These chimney valves allow free passage for air from an opening in the wall near the ceiling of the room into the chimney flue, but no passage in the contrary direction. With the proper contraction of the flue near the  fire, it causes the chimney draught to remove the heated foul air, accumulating constantly in the upper part of inhabited rooms, from the breath of inmates, the burning of lights, the odour of food etc, as certainly as the smoke of the fire. The valve allows passage only in one direction, like the clack valve of the common pump. It consists of a metallic plate, very nearly counterpoised by a weight beyond the axis of motion, and turning on a sharp edge so that the slightest force can move it.

Number 4615    14th November 1821  Production and agency of heat in furnaces, steam and air engines,and in distilling, evaporating and brewing apparatus.

Number 6459    25th January  1834  metallic pens and pen holders.




Sir, - About two years ago since a correspondent in your columns invited attention to the fact that the great principle of Dr Arnott’s new grates – the consumption of smoke by cutting off the draught of air below and kindling the fire on the top – might be adopted in ordinary grates, without exchanging them for those of the new construction.

The plan consists in laying at the bottom (on the bars) a thin movable iron plate, fitted so as to cut off the draught from below; then by laying upon it fresh coal up to the top bar; and upon this foundation laying the paper and sticks; and covering the latter with the rubble overnight.

Having previously purchased one of the Arnott grates for a bedroom (which answered admirably), I acted on the hint of your correspondent, and now have ten fires daily lighted on the same principle. The result is all that could be desired – little or no smoke, a bright clear fire, and a diminished consumption of fuel. It will last all night in a bedroom, without requiring any attention.

After a two years trial, I may fairly recommend its adoption to your readers. The great obstacle is the ignorance and prejudice of the domestic servant, who will if she can, put a stopper on the innovation. But the thing if so simple that even ignorance and prejudice cannot stand against it where the master or mistress is firm at the outset. My servants are now quite reconciled to it.

The smoke of London proceeds mainly from the domestic fire. Here then is a scheme which, at a cost of only a few pence per grate, would in one week remove the dark cloud overhanging the metropolis – a feat surely surpassing the launching (?) of the Leviathan, and at less than a hundredth part of the cost.

I am Sir, yours obediently

December 21 1857