Retrospective Criticism. 235 



Not only, also, does Mr. Niven's horticultural stove exceed any thing here- 

 tofore erected in its suitability to all sorts of vegetable productions, but in 

 the manner in which it expedites their perfection : as, for instance, in regard 

 to the cucumber, Mr. Niven affirms that, in six weeks from sowing, cucum- 

 bers were cut from 18 in. to 2 ft. in length ! 



In conclusion, I beg to observe that there is nothing I should more desire 

 than to meet in competition with Mr. Niven and his pipe-heated vine borders, 

 with one which 1 should lay down on the old-fashioned plan, which, for Mr. 

 Niven's information, I will state in detail. It is as follows : let the border 

 be excavated 12 ft. wide, 3 ft. deep at the wall of the house, sloping to 4 ft. 

 at the walk, along the side of which is to be made a drain to carry off all 

 superabundant water. Let then the bottom be pared and beaten as smooth 

 and firm as it possibly can be made. Then fill in a layer of any dry rubbish, 

 brickbats, if to be had, to the depth of one foot. Over this let there be 

 closely fitted a sod, of from two to three inches thick, with the grass side 

 down, and over that the compost. The materials, and the component parts 

 of which being a matter of opinion, I shall leave every one to judge for them- 

 selves. Thus the border, when finished, would in compost be 2 ft. deep at 

 the wall of the house, and 3 ft. at the walk. A border prepared and planted 

 after this method, protecting the stems and roots with litter in winter and 

 early spring forcing, I will engage to furnish as well ripened wood, to produce 

 as early and as abundant a crop, and as well flavoured fruit, as Mr. Niven 

 can possibly do with his expensive pipe-heated border. Nay better ; for I am 

 convinced that to heat pipes encased in the earth, so that their influence shall 

 be felt one foot from the drain or cut in which they are laid, will cause the 

 earth to become baked to that consistency that every particle of that nutritious 

 matter which constitutes the food of the plant would be utterly destroyed. — 

 Catius. Belfast, March 9. 184.1. 



Comparative Temperatiire of different Years, (p. 147.) — I have perused with 

 much pleasure, and I trust some profit, the ingenious article on the subject of 

 temperature by N. M. T., though I differ from him in some particulars. In 

 the first place, instead of the average temperature not varying more than half 

 a degree, it will be found to vary as much as 5° ; so that the seasons would 

 appear to be not " invariably alike," but rather invariably unlike. A warm 

 summer does not always follow a cold winter; though this is frequently the 

 case. It is more certain that a series of cold seasons is succeeded by a series 

 of hot ones. I do not think plants can be acclimatised. They are, in my 

 opinion, immutable in their natures. A stunted exotic will bear, for instance, 

 more cold than one grown so as to exhibit its natural vigour; but take a cut- 

 ting from it, grow it as it grows in its native country, and it will be found to 

 possess its original suceptibility. Seedlings, even without crossing, do vary ; 

 and by always selecting the hardiest, a little may be done in the way of ac- 

 chmatising, in the course of successive generations, but not much. — N. 

 London, Feb., 1841. 



Archiiectural Objects in Gardens. — You cannot think how cordially I agree 

 with you in the opinion that no architectural object ought to rise out of dug 

 ground. To baskets, rustic objects, rockwork, and almost every thing, I 

 apply the same rule, and so outrageously fastidious am I on this point, that, 

 in English or turf gardens, I cannot bear to see even shrubs do so ; even the 

 dug clumps in the grounds I fill so that the plants overstep, as it were, their 

 bounds, and kiss the turf on each side, and cut or train them so as to main- 

 tain their form perfect ; but I detest to see that form marked out by a staring 

 piece of sodden earth. I could almost quarrel with you for digging round the 

 hillocks in the Derby Arboretum. — N. M. T. Feb. 1841. 



The hillocks alluded to are not to be dug, but only to be covered with short 

 grass till the plants are so far grown as to render this care unnecessary. (See 

 Gard. Mag. for 1841, p. 542.) 



Shriveling of Grapes. — In p. 170. I observe an article on the shriveling 



