Dec«mb«r 23, 18Gg. I 



JOURKAL OF HORTICULTURE AND COTTAGE GARDENER. 



501 



I think I before stated, though I have not the paper by me, 

 as there is a constant ciroulation of heated water in a saddle 

 boiler, the water which comes in from the return-pipe, having 

 been cooled aa it has gone through the pipes in the houses, 

 comes in contact tirst of all with the heated sides of the boiler, 

 then rises to the curved portion, and strikes against the upper 

 surface. If this upper surface were not heated by the current 

 of flame playing over it, it would either repel the water or help 

 to cool it ; but as the heated air from the fire is of necessity 

 hotter than the water in the boiler, it assists to heat the water 

 still more, and so helps the flow ; and as the flame passing 

 over the surface of the boiler also plays round the flow-pipe, 

 which it sarroundB, it add j additional heat at a most important 

 point. 



Mr. Woolfield corrects me in another point about the dia- 

 meter of the feed-pipe. 1 am aware he is right about the 

 pressure of water depending on the height of the column of 

 water in the pipe, but it is also true that when hydraulic pres- 

 sure is applied to water in a small pipe it is greater than when 

 applied to a large one. I may have overrated it, but as the 

 feed-pipe has to relieve the boiler of the pressure caused by 

 expansion in boiling, the larger the size of the feed-pipe the 

 more easily the pressure is relieved. Many leaks in joints are 

 owing to a small feed-pipe, and it will always be noticed when 

 a joint does leak it leaks far more when the water in the boiler 

 is very hot. 



And now I must make a few remarks upon Mr, Woolfield's 

 paper, in which he gives directions for the quantity of piping 

 required to heat a house a certain number of degrees of heat 

 above the temperature of the atmosphere. He tells us the 

 quantity of air to be warmed per minute is Ij cubic foot for 

 each foot superficial of glass the house contains — to be warmed 

 how much ? The radiation of heat from a house does not 

 depend so much on the difference of temperature between the 

 external and internal air as on the force and the direction of 

 tiie wind, as regards the Burface of glass exposed. This is 

 such a variable quantity that no general rules can be laid down. 

 One night two weeks ago, with the thermometer at 25°, a small 

 house cooled so rapidly that, although there is a flow and return 

 pipe at the back of the house, it was found necessary to light 

 a fire in a flue which used to heat the house previously to the 

 hot-water pipes being put into it, and although a good fire was 

 kept up in the furnace the thevmometer inside fell to 40°. The 

 nest night the external temperature was as low as 19', but the 

 temperature in the house never fell below 45° without the flue 

 being used at all. In reckoning the radiating powers of glass, 

 the angle of the roof has also to be considered. 



Again, I do not agree that two rows of 2-inoh pipes are supe- 

 rior in economy to one 4-inch pipe, because the water in the 

 2-inch pipes cools down twise as quickly, and, therefore, though 

 it may require less fuel in the first instance to heat them, it 

 requires much more afterwards to keep the heat up, and for 

 nightworfc this is the most important point. 



Again, he gives 125°, a fixed quantity, as the excess of tem- 

 perature of the pipe above the surrounding air. This, I need 

 hardly say, will vary with the diiierence of distance from the 

 fire, and with the fire itself. Again, he gives 222 as the number 

 of feet of air raised 1" per minute by 1 foot of 4-inch pipe. 

 This, also, which he gives as a fixed quantity, must vary accord- 

 ing to the heat and also the position of the pipe, and the radi- 

 ating power of the external atmosphere. In fact, I think I may 

 fairly say that all the data which he gives as fixed rules for 

 finding out the necessary quantity of pipes are variable and 

 nncertain. 



One square foot of boiler for every 5!) feet of pipe may be a 

 very good rule ; but on this head, again, doctors differ, as Mr. 

 Weeks, in his pamphlet on greenhouses, &o., gives 25 feet for 

 200, 250 feet for 4000, 400 feet for 10,000. I am aware that in 

 this Mr. Weeks calculates every surface of any sort in the 

 tubular boilers, and I also think there are great discrepancies, 

 e.specially in the last two items, where I'O feet additional sur- 

 face has to heat (i(H)O additional feet of pipes, whereas a boiler 

 with 150 feet of heating surface in the same list is calculated 

 to heat 1500. I liave only quoted this to show there is great 

 difference of opinion on this head, and I am now heating tho- 

 roughly and efficiently nearly 450 feet of piping \(ith a boiler 

 which, according to Mr. Woolfield's method of calculation, 

 would only be sufficient for about 300 feet ; but then I calculate 

 the exterior and upper surface as an additional source of heat, 

 which Mr. Woolfield does not. 



What Mr. Woolfield states as to unnecessary depressions and 

 rapid curves cannot be too strongly insisted upon, and that is 



another reason in favour of 4-inch pipes over 2 inch, as there 

 is less friction, and water flows more freely. Let me again 

 repeat that the position of pipes, so as to allow free radiation, 

 is most important ; and if persons do not believe in radiation 

 of heat downwards, let them place some pots 2 feet below hot- 

 water pipes and see how rapidly they will dry; or, again, fill a 

 bottle with water, and put it flat underneath a grate, and 

 another bottle of an equal size at the same distance in front of 

 the fire, and see which will be heated first. I would also 

 impress on your readers that the laws for boilers for generating 

 steam, for boilers for the circulation of hot water, and ordinary 

 boilers, such aa those set at the side of a kitchen fire, are not 

 the same. — C. P. Peach. 



APPLICATION OP MANURES. 



I 3I0ST Bay I was much surprised at seeing the following 

 remark, " When Professor Voelcker speaks of no fear of waste 

 if the soil contains clay, he only refers to what is washed into 

 the soil by the rains." The whole tenor of his argument goes 

 to show that little or no loss can be sustained by spreading 

 manure, whilst an enormous loss is usually sustained by rotting 

 manure in heaps exposed to rain. He very properly says " if 

 the soil contains clay," because the soluble ingredients would 

 wash through some poor sandy soils if put on too long before 

 the crop intended to be benefited were sown. From the edi- 

 torial remarks it would also appear that there was a difference 

 of opinion as to the propriety of burying manure as soon as 

 convenient. Now I think this is hardly a fair inference. All 

 I contend for is that manure takes so little harm from sun and 

 wind when spread on the ground, that it is fooUsh to keep it ia 

 heaps when rotten manure is not a necessity, as in the case 

 of sandy laud. Then, again, I cannot agree with our Editors 

 " that the guano latitudes are characterised by a singular 

 absence of rain." From what I have gathered of those regions 

 rain very seldom falls there, and those places like Peru, where 

 the least rain falls, send us guano which is richest in salts o£ 

 ammonia. From this I gather that if there were no moisture 

 there would be no loss. With regard to the value Of any car- 

 bonic acid which could be lost by spread manure, I should say 

 it would be about equal in value to that given off by the " old 

 slick." 



There is one point in the editorial remarks which appears 

 worthy of consideration — " Urine rapidly decomposes in the 

 litter of a stable." No doubt it does when the stable is warm 

 enough to induce fermentation, and when each fresh supply of 

 urine comes in contact with urine undergoing change. How 

 long will a sound Apple remain sound when in contact with a 

 rotten one? Bat who ever smelt ammonia very strong in a 

 cold clean stable ? and where it is most abundant how little is 

 necessary to produce the effect perceived. Can anyone contend 

 that urine exposed to sun and wind is under the same conditions 

 as urine in a damp, warm, and close stable? I keep eight 

 horses myself, but if my stables smelt strongly of ammonia I 

 know some one would hear of it ; nor do my men use gypsum 

 or anything else to fix the ammonia. Thinking that Professor 

 Voelcker was most likely to know what he intended to teach, 

 I sent him the .Journal of December 2nd, and asked him to be 

 kind enough to state whether the inference drawn from his 

 essay was correct, and he very courteously sent me the follow- 

 ing reply, which, as far as I am concerned, closes the matter. 

 The subject to me is one of great interest, because it is of great 

 importance to me personally. Paying as I do some hundreds 

 a-year for manure, besides what I make on my own farm, it 

 would not be pleasant to think a good deal of it had been 

 wasted ; still, it would be much worse to pursue such a course 

 in error. — J. K. Peabson, Cliilwell, Notts. 



DR. VOELCKER'S letter. 



" In reply to your note, I beg to say that the Editors of The 

 JocRNAL OP Horticulture do not give a correct explanation 

 of my decided opinion that farmyard manure spread out on the 

 field loses no fertiUsing matter by exposure to wind and sun. 

 My opinion rests on experiment, and not on mere speculation ; 

 and the practical direction which I always give to my farming 

 friends is. Take your dung on the field at once, and wait till 

 the land is in a fit state to be ploughed up. I have noticed 

 over and over the mischief which is done by ploughing in 

 manure in wet weather when the soil was not in a fit condition 

 to be worked by men or beasts. In clay soils, especially, more 

 harm is done by the plough and horses' feet than good by the 

 manure. It is, therefore, most desirable that agriculturists 



