and of Rural Improvement generally, during 1839. 711 



surface was as low as 4*5° below zero ; and that it did not fall 

 within 5° of freezing at the depth of 2 ft. This circumstance 

 accounts for so many trees having sprung up again, which were 

 killed down to the ground, and proves the immense importance 

 of mulching the ground about the roots of tender plants. If 

 the frost at zero cannot penetrate through a mass of solid moist 

 earth 1 ft. in thickness, so as to freeze it, it will probably not 

 penetrate at all through a stratum of 6 in. of loose litter, leaves, 

 or other matter, so arranged as to throw off the rain, and remain 

 dry. Almost everything in mulching depends on the mulch 

 acting as a roof to the soil, and carrying off rain or melted 

 snows to 2 ft. or 3 ft. distance from the stem of the plant. If 

 the mulch, instead of conveying off the rain, allows it to sink in, 

 it will, in many cases, do more harm than good, by moistening 

 the soil, and lowering its temperature. The importance of fer- 

 mentation in fitting food for becoming nutriment to animals, and 

 organised matter for becoming manure to vegetables, has been 

 alluded to in our General Notices (p. 186.), and also in p. 648. 

 Various articles on soils, draining, on the choice of seed, on 

 varieties, and on different other scientific subjects, will be found 

 under the same head, which, though not altogether new, are yet 

 placed in a popular light, so as to be understood and applied by 

 the practical man. On the temperature and moisture of the 

 atmosphere of hot-houses, and relative subjects, some interesting 

 papers will be found in the present volume, by Mr. Wailes 

 (p. 506.), Mr. Beaton (p. 552.), and Mr. Ellis (p. 481.); but 

 much still remains to be done in this department of house cul- 

 ture, which will probably not be accomplished till we have a 

 more accurate knowledge of the different natural climates 

 throughout the world. In systematic botany, Dr. Lindley has 

 made what appears to us an improvement in the primary divisions 

 of the vegetable kingdom ; but, as this scarcely comes within the 

 limits of our plan, we refer to the Botanical Register for 1839, 

 p. 76. to 81. of the Monthly Chronicle of that work. 



New Agents of Culture. — Of new gardening implements or 

 engines, but few occur to us as having been introduced or be- 

 come popular during the year, which are worthy of notice. 

 Rogers's conical boiler for heating hot-houses by hot water ap- 

 pears to have the preference over most other forms for houses 

 and pits of small size, and, judging from the experience had of 

 it in the Horticultural Society's Garden, deservedly so. The 

 form has been more or less in use for a number of years, but 

 failed to attract much attention till made of cast iron by Mr. 

 Shewin, an ironmonger at Sevenoaks, in Kent. The boiler is 

 formed of one cone placed within another, both cones being 

 truncated ; the bottom of the inner cone being the grating on 

 which the fire is placed, and the space between the cones, which 



