General Noiiccs, SS 



tube d to tlie boiler ; thus producing a continued current of hot water 

 through the heating tube g. In order to raise the heated water to a higher 

 level, a close box (i) is affixed to a square chamber (A) above the boiler, from 

 which box the water ascends by the pipe / into a receiver (m) at the 

 top, and thence flows by the pipe or tube 7i round the building to be 

 heated in the same Vv'ay as through the tube g already described, and, 

 having performed its circuit, descends by the pipe o o into the cistern. 

 Such is the plan proposed by the patentee ; but the principle upon which 

 the water is said to rise in the pipe I rather than the pipe o does not 

 appear. The third featvu'e of the invention is shown at p, where a large 

 pipe is intended to carry up the heated water from a close vessel similar to 

 2, inserted into the tube g ; and within this large pipe is a smaller one for 

 bringing down the water again. The fourth suggestion is, to adapt small 

 pipes, passing alongside of the tube g, and branching off, if necessary, to 

 the sides, in order to convey the heated water into other parts of the build- 

 ing. These may be employed when there is but little fire in the furnace, 

 and, consequently, but a small quantity of heated water will be put in cir- 

 culation : to employ these small tubes in the way proposed, it will be neces- 

 sary to close the entrance tube g, and also the exit of the tube h, in 

 order to prevent the circulation going on in those tubes." (^N'eivton's Jour- 

 nal, May, 1830.) 



Heativg and ventilating Hot-houses. — There is a paper on this subject by 

 George Knowles of Ripon, in N'ewton's Jounial for June, in which a claim 

 is made for novelty in accomplishing the object without either " distern, 

 return pipe or pipes, or water retained upon the top of them for producing 

 vapour ; and a general tone of pretension assumed, which, to say the least 

 of it, invites to criticism." The present plans, the writer goes on to say, 

 " are far, very far, from being the best that the system of heating hot- 

 houses by boiling water is capable of being reduced to," This may be the 

 case ; but, we confess, we cannot discover a single step in advance indi- 

 cated in the paper before us, either in heating or ventilating ; Mr. Cottam 

 having, in repeated instances, employed only one pipe, and Messrs. Bailey 

 having moved shutters by machinery in the wall of a stove opening into 

 the back shed, at Knowle, in Kent, in 1819. (See also Vol. III. p. 305.) 

 Mr. Knowles uses the expression boiling v^^ater ; but, to heat with economy 

 of fuel, the water should not be raised high, but made to circulate with 

 rapidity. Kewley's plan (Vol. VI. p. 377.) is admirable in this respect* 

 At Mr. Colville's, the water in the boiler is never hotter than to admit of 

 holding the hand in it, though the hot-house is raised to 70° j the difference 

 between the temperature of the air and the Vv'ater is probably not more 

 than 20°. Such are the advantages of a rapid circulation. A very little 

 reflection will convince any one that, where water is made to boii, there 

 must be a much greater waste of heat by the chimney or flue than where 

 it is only raised to 90° or 100°. Mr. Knowles proposes to have openings 

 in his pipe to admit vapour at pleasure. This is neither new nor of much 

 consequence : every gardener knows that if he has once got heat he can 

 easily produce steam ; and it is much cheaper to raise steam by syringing 

 the house, and watering the floor, than to boil water in order to obtain 

 steam. But lest Mr. Knowles, whom we had the pleasure of seeing here 

 about a year ago, should think that we are not doing him justice, we shall 

 let him speak for himself: — 



" The boiler may be of the usual size and form, suitable to the extent of 

 space intended to be measured by the fire-flue and boiling 'water ; but it 

 must have its top firmly covered, and in the cover a slight sell-acting valve, 

 very easily worked, that a little steam may be retained upon the surface of 

 the v/ater, which gives a quicker motion to the water flowing through the 

 pipe ; I say pipe, for I have only one pipe in the whole apparatus. The 

 upper aperture in the boiler to be placed 6 in. below the top ; and from this 



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