VINERIES. 



327 



there be fitted with zinc ventilators. By 

 means of these ventilators, the warm air 

 can be made to act equally on every part 

 of the border. For instance, the ventila- 

 tion of the warm-air ducts nearest to the 

 origin of the flue being shut, the air 

 would pass on to the next open ones. 

 The floor of the border should be formed 

 of concrete, and at g, in the transverse 

 section, is a rubble drain to carry off the 

 water from the concrete to a drain, h. 

 At i are apertures for the purpose of ad- 

 mitting cold air to the bottom of the 

 arched chamber to displace the heated 

 air, which, being lighter, will rise into 

 the perforated air-ducts, and, partly dif- 

 fusing itself through the draining mate- 

 rial into the soil, the remainder will pass 

 into the house. From this will arise the 

 collateral advantages of being able, at any 

 time, to cause a circulation of air in the 

 interior of the house, which will be found 

 congenial to the health of the vines, and 

 whatever other plants it may contain. I 

 may here remark," he continues, " that 

 the warm air in its passage to the border 

 cannot be otherwise than moist, as the 

 rains that usually fall during winter, 

 spring, and autumn, will always cause a 

 sufficient moisture about the sides of the 

 chamber, which, being converted into va- 

 pour by the heat from the flue, will pass 

 with it into the border. From the out- 

 side of the stoke-hole should be brought a 

 current of air to the end of the chamber 

 next the boiler, to drive the heated air 

 from that part in the direction of the 

 warm-air ducts. The smoke, by passing 

 along the flue, will lose a great part of its 

 blackness, and will appear more like 

 steam when it leaves the chimney. This 

 of itself will be almost equivalent to the 

 expense incurred j while the soot can be 

 easily collected at k k in the ground 

 plan." 



The advantage of such an arrangement 

 as this cannot be doubted ; and the colder 

 the locality, and the more uncongenial 

 the soil to the culture of the vine, the 

 more important this or a similar arrange- 

 ment will be. Our own opinion of the 

 matter is, that hot water would be a 

 better medium for diffusing heat under 

 such circumstances than hot-air or smoke 

 flues, as the former could be propelled 

 through the various ramifications with 

 greater certainty and equal effect. Entire 



earthenware tubes, however, would have 

 to be substituted for perforated ones; 

 and the ends of the tubes entering 

 through the front wall of the house, 

 would require to be moulded with a bend 

 presenting their orifices upwards instead 

 of sideways. 



In a leading article in "The Gardeners' 

 Chronicle," (1847, p. 555.) the talented 

 editor remarks, in speaking of vine bor- 

 ders : "In general, vines are treated as a 

 man would be, if exposed to a steam bath 

 with his feet in ice. The necessity of 

 providing some means for warming the 

 borders of vines to be forced (we will 

 even say grown) in a climate like this, 

 will be obvious when we compare the 

 temperature of the earth in the south of 

 France and Great Britain. The mean 

 temperature of the earth near London, in 

 the three first months of the year, may 

 be taken at 38° ; that of Marseilles or 

 Bordeaux will be at least 65°. The mean 

 temperature of the earth near London in 

 July and August is 62° ; that of Mar- 

 seilles about 78° ; and of Bordeaux 77°. 

 We will ask whether it is probable that 

 such differences in the soil can be unim- 

 portant to the plants which grow in it 1 " 

 After stating the temperatures of the 

 soil in various places, he proceeds — " It 

 is therefore interesting to inquire whether 

 the temperature of the earth in which 

 plants grow may not be inferred from 

 that of the air which rests upon the sur- 

 face. It has been shown, in the ' Theory 

 of Horticulture,' p. 95, that in October, 

 near London, the mean temperature of 

 the earth has been found 3° or 4° above 

 that of the air, although, in general, the 

 difference is not more than a degree, 

 or a degree and a half, in favour of the 

 earth. The permanent heat of the earth 

 may therefore be regarded as being always 

 higher than the mean of the air ; but the 

 amount of difference will be regulated by 

 the temperature to which the earth is 

 exposed, and by its own conducting qua- 

 lities. It seems to us, however, that for 

 gardening purposes the temperature of 

 the earth may be taken, on an average, 

 5° above the mean temperature of sum- 

 mer in warm countries — very often more, 

 seldom less ; so that if the mean tempe- 

 rature of Rome in the hottest month be 

 77°, it is probable that that of the soil, at 

 the same time, will not be less than 82°. 



