Poljrani-y 1(1, lt74 ) 



JOUENAL OP HOETIODLTUBE AND OOTTAQB GARDENEE. 



107 



when tho water is 100" above the temperature of the surroniul- 

 ing air. But as 1 lb. of coal raises 12,0(l0 lb."!, of water 1 ", it 

 will raise .';-l25 lbs. (that is to say, the water in 1 Hiieal foot of 

 pipe), liliOl", or the water in ft't lineal feet 10'8G°. Hence 1 lb. 

 of coal per hour will keep 55 feet of -l-inch pipe at a steady 

 temperature of 100' above the surrounding air, or 5500 feet 

 1° above the surrounding air. Then, if we take j> to represent 

 any different length of pipe, and il to stand for any other dif- 

 ference between the temperature of the pipe and of the air in 

 the house, we shall get the following equations, corresponding 

 to those given for the heating of air, 



5500C , 65C0O _ ])d 



{^■)i>. = —r> «= ,, ' ^ = Zm- 

 The first of which may be expressed in words thus : — ■ 



To find tho length of pipe which a given number of pounds 

 of coal per hour will maintain at a given temperature, mul- 

 tiply the pounds of coal by 5500, and divide by tho difference 

 between the heat the water is intended to be kept at and the 

 intended heat of the house. 



The other formula' may bo reduced into words in like 

 manner. 



Finally, if we wish to e:(press any one of the quantities 

 p, d, D, and S in terms of the others, by taking from the 

 formulas (1) and (2) the common value of C, and equating, we 



obtain ^^ = J^g. From which it follows that 



,„ , 6500ZJS UDS , , 117)8 



^^ = iifl "early. 



The first of which formula; may, for an example of the rest, 

 be expressed thus : — 



To find the length of pipe which, at a given temperature of 

 the water, will heat a structure having a given superficies of 

 glass to a given temperature, multiply the superficies by eleven 

 times the intended difference between the outside and inside 

 temperatures, and divide the product by fifteen times the 

 intended difference between the heat of the water and the air 

 of the house. And having thus found the value of y, if we 



substitute it in the equation C = ^-^^ we shall get the quantity 

 of coal necessary to give the desired result in the given con- 

 ditions. 



The data on which these expressions and rules are founded 

 are well known ; but the method of deriving them and the 

 formula) for calculation are, so far as I know, new, and may 

 therefore have admitted error. I shall therefore be glad if any 

 of your correspondents will kindly point out any mistake they 

 may discover. Subject to such correction, the formuhe will 

 be found very useful in adapting heating apparatus to any new 

 structure or in testing the performance of any existing arrange- 

 ments. — J. Boyd KiNNE.iit. 



D 



^^,,and 



TO YOUNG GARDENEBS ON RENOVATING OLD 

 FRUIT TREES, AND OTHER SUBJECTS.— No. 3. 



It is from youthful vigorous trees that wo must remove large 

 branches and roots. I am well aware that large trees when in 

 sound health and favourably situated will bear the removal of 

 large limbs without apparent injury, and the wounds will heal 

 rapidly; but such amputations often lay the foundation of 

 decay. This also arises in many cases from tho roots being in 

 a cool wet subsoil, where the central ones become decayed, 

 and the evil gradually extends to the body of tho tree. To 

 head-down a tree in such a condition for grafting, or to form 

 a new head, or even to cut oft' any part with the object of im- 

 proving the tree, will only end in disappointment. In all such 

 cases it is well to consider whether it is not advisable, if the 

 tree can be spared, to at once replace it. If this is not to be 

 done, let the large branches alone, but thin-out the small ones, 

 and remember that the roots play an important part in re- 

 storing vigour. 



If much younger trees are not thriving or have been neg- 

 lected, and it is thought necessary to head-down or cut back 

 for grafting, yet if the roots are in difficulties, the foliage of 

 the young wood from the grafts will in a year or two assume 

 the appearance of having been plated with silver, be turned to 

 a glossy milky colour, or in other cases to a sickly yellow. I 

 have seldom seen such trees recover if not taken in hand 

 immediately. If left for a year or two they may be at once 

 removed, as they will never do any good. We should secure 

 a stock of young trees to take their place — not mere maiden 

 trees, but those of four or five years' growth, which may be 



expected to bear some fruit at once. It is somewhat strange 

 that it is quite possible a tree may present no sign whatever 

 of unnatural-coloured leaves before tho branches are cut off, 

 although in cool subsoils combined with almost sunless aspects, 

 such as north borders, wo find single branches assuming this 

 character : cut them off, and the like will appear again. It is 

 an unmistakeable sign that all is not right at the roots, and 

 the sooner these are brought near the surface in new soil the 

 better. To head-down such a tree with its organisation so dis- 

 ordered would be folly. Until its foliage appears in its natural 

 character it is best to case-off' any outlying branches, and care- 

 fully lift the roots and remake the border. 



Cutting off large branches is a frequent means of bringing 

 this disease about with certain varieties, the sudden shock to 

 tho whole system being more than the tree can endure. I will 

 give an instance. From a young Morello Cherry tree in a north 

 border it was deemed necessary to take the centre branch ; 

 before doing this the tree was, to all appearance, in tho very 

 best of health, yet the following summer it produced this 

 unnatural-coloured foliage and refused to grow an inch. In 

 another case some, to all appearance healthy, bush Apple trees 

 were headed-down and grafted ; they made rapid growth and 

 formed nice bushy heads, yet in tho third year they, too, had 

 this sickly hue and ceased to grow. In this instance the posi- 

 tion was the reverse of that in which the Cherry was planted, 

 but the subsoil was bad, and the surface soil unfavourable to fruit 

 trees. These are not solitary cases ; I have witnessed hundreds 

 similar, and I contend, like Mr. MiiUer, that more trees are 

 destroyed by the amputation of limbs than all other causes put 

 together. I have always found that trees on a dry open subsoil 

 bear severe pruning better than those on cool soils, but would 

 advise that on no occasion whatever, if a tree is to continue to 

 be prosperous for any considerable time, should large branches 

 be sawn off' — for instance, branches of or 8 inches in diameter. 

 Any large wound which may be made should be immediately 

 covered with a waterproof composition to preserve it from 

 the action of the atmosphere and from insects. 



There is a right and a wrong way of eutting-off limbs. 

 Almost invariably we see trees headcd-down with the branches 

 severed horizontally, forming a receptacle for all noxious 

 substances to penetrate into the wound. Avoid this at all 

 times, and always cut in a vertical direction. I am of opinion 

 that there are certain ages beyond which trees cannot have 

 their heads or hmbs taken off with any chance of the wound 

 healing over. In every garden and orchard may be seen clumsy 

 wounds left from 3 to inches from the main stock or branch, 

 and the decay can be traced passing downwards without the 

 least efl'ort on the part of the surrounding bark to cover the 

 wound ; the tree gradually sinks, and at last refuses to proilviou 

 even a leaf. 



I remember that about twenty years ago some orchards were 

 to be converted into market gardens. Many of the trees were 

 large, sound, and vigorous, but bore small useless fruit ; they 

 were headed-in, but not closely, and grafted well out on the 

 tops of the branches, placing in many instances on one tree 

 from 150 to 200 grafts of the best-bearing varieties, which 

 were generally of slow growth. Immense crops were pro- 

 duced for a few years, then the foliage assumed a sickly 

 colour, and died. The trees paid well even at this time, and, 

 of course, young trees were growing up to take their place ui 

 tilling the baskets for market. This is jnst what ought to be 

 done in private establishments. It was evident, however, 

 that the union between the stock and the scion was never a 

 happy one from the first. The grafted trees made vigorous 

 eft'orts to replace the limbs which had been cut off by push- 

 ing every hidden eye into growth, and if these had been 

 allowed to appropriate the abundant supply of sap sent up by 

 the roots, I have little doubt the trees would now be in a 

 healthy state. In support of this view I may state that the 

 trees which were grafted with stronger-growing varieties are 

 to this day as vigorous as ncid be, and this I ascribe to the 

 heads being capable of elaborating the abundant supply of 

 nourishment provided by the roots, and returning to these 

 all that was wanted to support the underground working 

 power. In the case of the slow-growing varieties placed on 

 strong-growing stocks there was no such balance, as for the 

 large supply of crude food sent up by the roots there was no 

 machinery to elaborate it properly : hence decay set in. In 

 heading-down a large tree, then, would it not be advisable to 

 shorten the roots at the same time, in order to preserve the 

 balance, or make it incline to whichever side we wish '? Thus, if 

 wo want to render the bead more vigorous we encourage the 



