1869.] fosteb'b boiler. 165 



places. Skin smooth, of a beautiful pea-green colour, with a slight patch of 

 russet round the stalk. Eye small, open, set in a very shallow angular basin, 

 almost level with the surface. Stalk long and slender, inserted a little on one- 

 side -without depression. Flesh greenish white, delicate, buttery, and melting, 

 very solid, with scarcely any core. Flavour rich and pleasant. 



This is a Pear which we anticipate will take a high rank. In appearance it 

 is somewhat like a Glou Morceau, but is distinguished by the very long slender 

 stalk and the deep green skin. The flesh resembles that of the Marie Louise and 

 Glou Morceau. Ripe in October. Grafts of this variety were received by the 

 Society in 1860 from the Societe Imperiale et Centrale d'Horticulture du 

 Departement de la Seine Inferieure. H. 



FOSTER'S BOILER. 



*E borrow from the Gardeners' Chronicle the following illustrations of a new 

 Hothouse Boiler, which has been introduced with very satisfactory 

 results, by Mr. Pearson, of Ohilwell. It will be seen that this is a 

 modification of the good old saddle-boiler, with certain additions, which 



appear calculated to make it more effective. Its construction will be understood 



from the subjoined figures and description : — 



When a young man, I was always anxious to see the process of manufacture a3 carried on 

 in large establishments. In looking over the great Butterley Ironworks, near Derby, I 

 remember having been struck with the first reverberatory furnace I came to. Though I knew 

 chemists considered the flame the hottest part of a fire, and was not ignorant of the effects of 

 the blowpipe, I was still surprised to see the flame alone employed in melting iron. This was 

 a lesson I never forgot. Having 21 houses, some of them 100 feet long, and 24 to 30 feet 

 wide, I have had a good deal of experience in heating ; and have nine different kinds of boilers 

 in use, but I have never been satisfied with any of them, for it has always appeared as if the 

 makers had ignored the power of flame by allowing it to strike against a brick wall. 



Of all the boilers invented, I think the tubular ones are the worst and the most unphilo- 

 sophical. No doubt the tubes in a locomotive boiler suggested the idea; but because fire 

 carried through tubes surrounded by water is found to heat water quickly, it does not at all 

 follow that water contained in tubes which enclose a fire should be rapidly made hot. A 

 boiler on this plan can be made of any size, and will hold any amount of fuel, and this I con- 

 ceive is its only advantage. A tubular boiler must be surrounded by brickwork, and were it 

 fed with small coal and slack, would be choked ; it is, therefore, necessary in practice to use 

 large coke, a most expensive fuel ; it requires a very deep hole to stand in ; the flame must 

 pass by and between but few of the tubes into the flue, so that the heat will be in a great 

 degree wasted ; then each tube being caulked into a ring of metal at each end, the large 

 number of joints acted upon by the fire is sure to give rise to leakage, or, if not, the unequal 

 expansion of the metal is likely to crack it. To put hard water into a hot-water apparatus 

 at all is very bad policy, but it must quickly destroy a tubular boiler. The water-way is so 

 small that any incrustation must soon fill it up, and it will in that case soon burn or crack. 



A serious objection, common to nearly all boilers, is that they are necessarily surrounded by 

 brickwork, which must become red hot, and the return pipes must pass through this before 

 entering the boiler, so that unless special precautions are taken to prevent it, return currents 

 will be set up, and the circulation impeded. 



These objections do not apply to some of the improved wrought-iron boiler3, but wrought- 

 iron boilers rust so rapidly, particularly when not at work, that this circumstance alone is a 

 very grave objection to their use. 



Impressed with these ideas, I have for years been trying to induce Mr. Foster, who builds 

 my houses, to make me a boiler, and at last I have got into work one which quite equals my 

 expectations ; in fact, I have seen nothing like it for quickly heating a large body of water. 

 The boiler is 3 ft. 9 in. in length, and as the fire never comes in contact with anything but 



