564! Coping for Garden Walls. 



the frost sets in, remove them to a room, or any other place 

 where they may be protected from the cold. A small win- 

 dow, with a shelf in the centre, will contain 200 plants. If 

 the same window were employed for holding full-sized plants, 

 two common-sized pelargoniums would fill it. In about the 

 middle or latter end of March, plant each rooted cutting in a 

 small pot, and put them into any sheltered situation until 

 the season be fit for transplanting them in the open air. By 

 this method a supply of young plants may from year to year 

 be obtained, with scarcely any trouble. 



I am, Sir, yours, &c. 



Peter Mackenzie. 

 Stirlingshire, April 22. 1833. 



Art. XIII. On Coping for Garden Walls. By Mr. Archibald 



GORRIE. 



Sir, 

 In the Encyclopcedia of Gardening (§ 1557.) it is very 

 justly observed, that " it is not settled among gardeners 

 whether the coping" of garden walls "should project at all;" 

 and many feasible arguments have been adduced why they 

 should not. The are said to look clumsy if far projected, to 

 harbour vermin, to prevent genial showers from refreshing 

 the foliage : and all this, and a great deal more, may be very 

 true. On the other hand, however, it must be conceded, that 

 garden walls are generally built for affording a higher temper- 

 ature in order to raise the finer fruits, natives of warmer cli- 

 mates. It is also well known that the earth radiates heat in 

 the night-time, and under a clear and still atmosphere ; as any 

 substance which intercepts the escape of such radiated heat 

 into the blue expanse adds considerably to the elevation of 

 the temperature on the lower side of that substance com- 

 pared with that indicated on its upper surface. Whether 

 this proceeds from the " frigorific rays," being arrested in 

 their downward course, according to some who insist that 

 cold is a body, or from radiated heat arrested and returned 

 to the earth's surface by projected coping or other substance ; 

 be the cause which or what it may, few, I believe, of my 

 brethren, in this intellectual age, are so unscientific as to 

 deny the result. If any such there be, I must beg to refer 

 them to An Essay o?i Dew, by Dr. Wells (p. 252 — 254.), or 

 to your remarks on the same subject in the Encyclop(sdia of 

 Gardening, 3d edit. § 1206. Taking it for granted, then, 

 that, in clear and calm nights, projecting copings preserve a 



