26 Revieics. — Linclley'^s Theory of HorticiiUure. 



tions communinated to me by Sir John Herschel, it appears that the 

 teinperature of the earth, at the Cnpe of Good Hope, is often exces- 

 sive. On the 5th of December, 1837, between one and two o'clock 

 in the day, he observed the heat, under the soil of his bulb garden, 

 to be 159^; at 3, P. M. it was 150°, and even in shaded j)laces 119": 

 the temperature of the air in the shade, in the same jjarden, at the 

 same j)eriod, was 98° and 92°. At 5, P. M. the soil of the garden, 

 having been long shaded, was found to have, at 4 inches in depth, 

 a temperature of 10'i°. "On the 3d of Deceml)er, a thermometer 

 buried one quarter of an inch deep, in contact with a seedling fir of the 

 year's plantinir, quite heallhy, and having its seed-leaves, marked as 

 follows:— at lib. 25m. A. M. 148-2°, atOh. 48m. P. M. 149-5°, at Ih. 

 34m. P.M., 149-8°, at Ih. 54m. P. M. ISO-S"^, and at 2h. 4Gm. P. M. 

 148°." Sir John Herschel observes that such observations "go to 

 Bhow that at the Cape of Good Hope, in the hot months, the roots 

 of bulbous and other plants which do not seek their nourishment 

 very deep, must frequently, and, indeed, habitually, attain tempera- 

 lures which we can only imitate in our hot-houses by actually sus- 

 pending over the soil plates of red-hot iron. For it must be remark- 

 ed, thai heating the grounil from beloio would not distribute the tem- 

 perature in the same way." 



Book IT. treats "of the Physiological principles upon which 

 the operations of Horticuhure essentially depend;" and com- 

 mences with these remarks: — 



Every operation in horticulture depends for success upon a cor- 

 rect appreciation of the nature of the vital actions descril)ed in the 

 last book; for althoush there have been many good gardeners en- 

 tirely unacquainted with the science of vegetable physiology, and 

 although many points of ])ractice have been arrived at altogether ac- 

 cidentally, yet it must be obvious that the power of regulating and 

 modifying knowledge so obtained cannot possibly be possessed, un- 

 less the external influences by which plants are affected are clearly 

 unrlerstood. Indeed, the enormous difference that exists between 

 the skill of the present race of gardeners and their predecessors can 

 only be ascribed to the general diffusion, that has taUen place, of an 

 acquaintance with some of the simpler facts in vegetable physiology. 



In attempting to apply the explanations of science to the routine 

 of horticultural practice, it appears desirable, in order to avoid fre- 

 quent repetition, that all the subordinate details of the art should be 

 omitted, and that those general operations should alone be adverted 

 to, which, under manj^ different modifications, and in various forms, 

 constitute the foundation of every gardener's education. 



Canker and infertility of many of our finest fruits, have been 

 subjects of earnest inquiry and research. Various theories 

 have been advanced, and as many partial experiments, but all 

 with hitherto uniform success; the success of failure. The 

 past summer, of unusual drought, gave us, however, the most 

 remarkable crop of the delicious St. Michael pears, that we 



