Thomas Messenger’s Triangular Boiler

A tubular boiler differs from a saddle boiler in that instead of a single flat surface adjoining the furnace a series fully interconnected cast-iron tubes were used. This had the advantage of being more effective in heating the water; however, they reputedly suffered from higher fuel consumption and the tubes were susceptible to cracking. Early tubular boilers contained horizontal circular tubes and only later did they develop vertical tubular boilers. Horizontal tubular boilers typically required a much shallower stoke-hole than a boiler with vertical tubes. Occasionally the tubes were made as a single casting, which caused problems if defects arose. Later, ingenious methods were deployed, whereby if a problem arose it was possible to isolate the problem area whilst still running the boiler.

The following is an extract from Thomas Messengers’ successful 1856 Triangular Tubular Boiler patent application: –

My Invention consists of surrounding the fire with a number of triangularly or other shaped tubes, which form water spaces, extending from the front to back, and secured at each end by iron cement, or other suitable means, to sockets cast on inner plates, with sides and ends and flanges, to which are screwed front and back plates. By this arrangement a water space is formed between the inner and outer plates, which communicates with the tubes. Water admitted at the bottom or lower tube or tubes becomes heated, circulates freely through all the tubes and water spaces, and rises to an outlet at the upper part of the boiler. The furnace bars are cast with notches, and rest between the bottom row of tubes. The boiler, formed as just described, would only be applicable to heating purposes; and to convert into a steam boiler, I add a steam box or chest, which I cause to communicate with the water spaces, through which the water ascends and descends, and circulates though the power part of the steam chest. The steam fills the upper part of the chest, and may be taken off for any purpose required.

Figure 1 of the accompanying Drawings is a transverse section of this boiler, shewing the form of tubes and tubular fire bars; Figure 2, front elevation of the same; Figure 3, back elevation, shewing inlet and outlet pipes; Figure 4, longitudinal section of the boiler, shearing the connection of the tubes and the chambers; and Figure 5, a perspective view, with part of the brickwork removed. The same letters refer to similar parts in all the Figures.

A, A, is the brickwork of the furnace; B. B. are a series of triangularly shaped tubes, extending parallel or nearly so to one another from the front to the back part of the furnace. These tubes are secured at each end with iron cement in sockets a, a, cast on the inner plates C, C1. The plates C, Cl, are cast with sides, ends, and flanges. To these plates the front and back plates D, D1, also having sides, ends, and flanges, are bolted or otherwise fixed. By this arrangements a space marked A1, Figure 4, between the plates C and D, C1, and D1, is formed, and this space is in communication with the triangular shaped tubes of the boiler. Water is supplied from the inlet pipes B1, B1, and becomes partially heated before entering the tubes; after passing, through them, the water rises to the outlet pipe C11, to circulate through the pipes in a vinery or other house to be heated, and returns to the inlet pipes B1, B1. H flue or chimney through which the smoke passes; I is the furnace door; and K, ash-pit. To fit a new tube for a damaged one or to clean the boiler, it is only necessary to unbolt the places C, C1 or D, D1, or both, when the worn tube can be removed and a new one put into its place without in any way disturbing the remainder or injuring the brickwork of the furnace or boiler. The plates C, C1, and D, D1, being again secured, the furnace is complete as before. The boiler may be made capable of doing ally increasing the number and length of the tubes.

And having now described the nature of the said Invention, and the manner in which the same is to be performed, I declare that I claim,-

First the placing in a boiler of a number of triangularly or other shaped tubes, parallel or nearly so to each other, at such a distance and in such a position as to allow the heat of the fire to pass freely between or around them, in the manner herein-before described

Second, the constructing of the outer plates of the water-tight chambers in separate parts, in the manner and for the purposes herein-before described.

And, third, the general arrangement of the furnace and boiler, constructed and operating in the manner herein-before described, and represented in the Drawings hereunto annexed.


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His design was subsequently described in the Mechanics’ Magazine[1]:

In this boiler an arrangement of parallel triangular pipes is used, as shown in the engraving. The horizontal position of tubes, and the triangular shape, cause the gas in their upward current to rebound from tube to tube, so that before they can reach the flue, the whole of the heat is expected in the boiler. Rapid circulation of the water is caused by the action and re-action of the fire. Should the boiler require cleaning, it can be done by removing the ends which are made in separate parts. The fire-bars form water spaces.

Thomas Messenger was one of the early pioneers of the tubular boiler, which later became very popular, although those using vertical rather than horizontal tubes were more prevalent. He did have a number of competitors in the tubular boiler market. James Gray, of Danvers Street, Chelsea, London, developed one known as “Gray’s Oval Tubular Boiler[2]. It consisted of a double row of upright cylindrical pipes fitted into a hollow frame or water space with sockets at top and bottom, and standing over a concave cradle-like furnace, the bars of which consisted of horizontal water pipes. Mr. Ormson, Stanley Bridge, Chelsea, London, developed one called a “Patent Jointless Tubular Boiler”, which consisted of a single tier of vertical cylindrical tubes, connected by water spaces at top and bottom, “all cast in one piece[3]. Messrs Taylor and Sons, Harrow Road, Kensal Green, London[4] designed at least two boilers. One, a “Tubular Horizontal Boiler”, which consisted of long but small cylindrical tubes, arranged in a single series at the sides, and in a double series at the top. The other a “Double-chamber Corrugated Boiler”, essentially a modified deep saddle boiler with corrugated sides. Messrs John Weeks and Co., King’s Road, Chelsea. London, who, with their “Tubular Upright Boilers[5], was probably above all others, responsible for popularizing the tubular form of hot-water boiler. This boasted hollow bars with a large surface area exposed to the furnace and were claiming to have already sold 4,000[6]. As part of their marketing strategy, they were offering a ‘one boiler’ solution, whereby they were claiming that one of their boilers “could do the same work which hitherto has taken from six to twelve boilers[7]. At their Chelsea showground they had several boilers on display; one using 1,000 feet of pipe heating almost 16,000 superficial feet of glass; another boiler, 5ft. high by 3ft. 6in. diameter heating various houses connected to 5,000 feet of pipes. Several of their boilers were installed at the Duke of Leeds’ Hornby Castle; one connected to 10,000 feet of 4-inch heating pipe; another heating a 190ft. long conservatory, with the boiler located almost 500ft. away[8].


Messrs John Weeks and Co.’s Tubular Upright Boiler

Thomas Messenger’s triangular boiler was unique in that it had triangular shaped tubes instead of the standard circular tubes. Tubular boilers were, size for size, regarded as more efficient than a saddle type, as they contained a significantly larger heating surface.

Thomas Messenger argued that his triangular tubes presented a much larger surface area than circular tubes and regarded his boiler as being both more effective and efficient than either the equivalent circular tube boiler or the standard saddle boiler. Interestingly, he resisted the temptation to follow the trend of developing a vertical version of his tubular boiler, instead he continued to find ways of slowly enhancing his tried and tested horizontal boiler.

By April 1866, he was actively advertising his boilers having proudly claiming that he had sold around 500[9]: –

T.G. Messenger’s Boiler possesses all the advantages of the Tubular and Saddle combines, has hollow furnace bars, requires but a shallow stokehole, and exposes as much surface to the direct action of the fire as can possibly be obtained, the whole of which can be easily cleaned; and it is an important fact that out of upwards of 500 now at work made upon this improved principle not one has cracked.

It is difficult to understand how accurate this figure is as the same advertisement appeared on a number of subsequent occasions over the next few years, the last of which appeared on 28th May 1870[10].


Thomas Messenger Advertisement – The Gardeners’ Chronicle & Agricultural Gazette, 28 May 1870

Unsurprisingly, in his 1870 catalogue, he included his triangular boiler describing its’ advantages and recent developments:-

MESSENGER’S PATENT TRIANGULAR TUBULAR BOILER, for Heating by Hot Water, has been successfully tested by many years’ working, and has proved itself the most powerful boiler at present before the public. It is equally adapted for heating a large building or a small one, being made in various sizes to suit requirements. It has been successfully adopted for heating many hundred ui1dings of every description. The principle of this Boiler consists in the arrangement of Parallel Triangular Tubes, with Continuous Water Spaces at the ends of same, which arrangement, as will be seen by accompanying sketch, exposes a larger amount of boi1er surface to the action of the fire than any other boiler in use, whilst the principle portion of the tubes being directly over the fire receive the full amount of heat possible to be extracted from the fuel, by direct action, besides which, after passing the Saddle or lower part of the Boiler the fire is diverted and made to pass longitudinally under and over tile upper part of the Boiler, which part is connected to lower part by syphon, thus rendering it at the same time economical and powerful. In the larger sizes this Boiler, besides combining all the advantages of both a Saddle and a Tubular Boiler, the bottom of the furnace is composed of Hollow tubes, instead of solid bars, through these tubes the whole of the returning cold water is passed in its course to the boiler, thus causing a very rapid circulation, and at the same time preventing the burning of the tubes. The elevation of Boiler shown illustrates the form and mode of setting larger Boilers for heating more than 600 feet of 4in. pipe. The section shows form and mode setting Boilers under that size. The larger sizes are fitted with a newly-designed sliding Furnace Front, which will be found particularly convenient.

When he sold the business in 1875, the new owners also bought the rights to the boiler and continued marketing it until they developed a suitable replacement in 1881. Known as the “Loughborough” boiler it was even more successful, selling 7,000 in the first eight years[11].

A Messenger & Co.’s advertisement from December 1876[12] indicated that almost 3,000 triangular boilers had been sold. The advertisement continued to promote the virtues of the boiler that Thomas Messenger was using two decades earlier:-

“Combines all the advantages of the old Saddle, which is acknowledged to be the most economical, with the Tubular, the most powerful form of boiler. By the use of triangular tubes a larger amount of heating surface is exposed to the direct action of the fire than in any other form of boiler. The water bridge also received the most intense heat. Te boiler is made of cast-iron, which is admitted to be the best material as regards durability strength, &c. In consequence of the above advantages we are enables to supply boilers with a large amount of heating-power at very moderate rates. The power of this boiler can at any future time be increased by adding another row of tubes”.


Messenger & Co.’s Tubular Boiler Advert – The Gardeners’ Chronicle, 30 December 1876

From the surviving records, it is difficult to be definitive as to what proportion of the boilers that Thomas Messenger sold were his own triangular boiler as opposed to a standard saddle or bought-in boilers. The records rarely indicate the type of boiler; they normally simply refer to a “boiler”, often referring to a particular size of boiler. However, given that over the twenty-year period from 1856 nearly 3,000 units were sold, it is likely that no reference to the type of boiler probably indicates that tit was one of his own models.

Assuming that the April 1866 advertisement of 500 boilers sold was accurate; meaning another 2,500 were sold over the next ten years. An even distribution of sales over that period, would give a figure of over 200 per year. During the period from 1866 until 1874, the existing records show that sales or potential sales never exceed 100, with an average under 70. It is likely that the majority of the boilers mentioned in these records were triangular boilers, especially as less than 600 boilers are referenced over the period. These records relate to Thomas Messenger supplying complete heating systems, with our without other products or services. It is therefore obvious that he must have sold large number of boilers that are not referenced in the existing records. Presumably, these are individual units sold to users for them to install or to third-party installers.


Sizing and Pricing

By the end of August 1867 Thomas Messenger started numbering his boilers, this was a little over a month after he went into partnership forming The Star Foundry. Whilst this may have been a coincidence, Thomas Messenger may have used this as an opportunity to re-structure his range of boilers. No doubt, he used The Star Foundry to provide him with cast boiler components, to be assembled in his High Street boiler making shop. Prior to August 1867 boilers were simply referenced as “boiler to heat ….” or “boiler large enough to heat ….” with their own pricing structure. Prices started at £3 3s. and went up in guinea (£1 1s.) intervals to £8 8s, followed by one at £10, another at £12 and finally one at £25 simply described as “Large”, two of which were included in estimates for the Duke of St. Albans. After August 1867, the boilers were simply numbered between 1 and 14, with 1 being the smallest and 14 the largest in terms of heat output and probably in physical size as well. The opportunity was also taken to introduce a more structured pricing arrangement. Initially there were eight boiler sizes (1-8). Boiler sizes 9-12 appear in 1868; size 13 in 1870 and size 14 three years later. Over the eight-year period the most frequently recommended boiler was the size 2, averaging around sixteen per cent, topping the list on four occasions 1869, 1870, 1871 and 1873. Sizes 1, 3, 4 and 6 were the next most commonly recommended, averaging around eleven per cent, with size 1 topping the list in 1867 and 1869; size 3 in 1872; size 4 in 1870; size 6 in 1874. Throughout the eight-year period, there was a trend for the average size of boiler to increase, although it was by no means linear.

As mentioned previously, prior to August 1867 the smaller boiler prices started at £3 3s. ascending in guinea (£1 1s.) intervals up to £8 8s. Following the introduction of sized boilers, the pricing structure also changed, with if anything a slight price reduction, at least initially. Over the following years up to the end of 1874 prices increased by up to 73 per cent, although the average was less than 35 per cent. These figures can be misleading because for periods, especially in 1873 and 1874, Thomas Messenger levied a surcharge of up to 40 per cent of the ‘list’ price.

Boiler Size

Year of Introduction

Heating Capacity[13]
(linear ft.)

1870 Prices[14]



























































  1. The Mechanics’ Magazine, Volume 66, January 3rd – June 27th 1857.

  2. The Gardeners’ Chronicle and Agricultural Gazette, 24th May 1862, page 476.

  3. Ibid.

  4. Ibid.

  5. Ibid.

  6. The Gardeners’ Chronicle & Agricultural Gazette – 16th August 1856.

  7. The Gardeners’ Chronicle & Agricultural Gazette – 12th January 1856.

  8. The Gardeners’ Chronicle & Agricultural Gazette – 16th August 1856.

  9. The Gardeners’ Chronicle and Agricultural Gazette, 21st April 1866.

  10. The Gardeners’ Chronicle & Agricultural Gazette, 28th May 1870.

  11. Wills’ Loughborough Almanac & Street Directory, 1889.

  12. The Gardeners’ Chronicle, 30th December 1876, page 832.

  13. Length of 4-inch pipe.

  14. Prices include delivery to Loughborough Railway Station only.

  15. Price at introduction in 1873.