Observations on Insects affecting the Turnip Crops. 323 



Fig. 34. The crown of a small Turnip, with all the leaves cut off ex- 

 cepting one. 

 Fig. 35. A small portion of the stem of a Turnip, with two of the seed 

 pods remaining. 

 Obs. — All the figures are drawn from nature^ excepting 15, 19, and 

 20; and the numbers with a * attached, indicate that the objects 

 referred to are represented much larger than life. J, 



London, August, 1842. 



[The Copyright of this Paper is reserved by the Writer.] 



XXIII. — On the Use of Burnt Clay as a Manure for Heavy 

 Clay Soils. By Francis Pym. 



To Ph. Pusey, Esq. 

 My dear Sir, — I now send you, as you wished, a report of my 

 experience in the use of burnt clay, which I have applied to land 

 more or less for the last seventeen years. 



For the first ten years it was upon a heavy clay-land farm in 



Cambridgeshire, about two miles south of Caxton, on the old north 



road, and for the last seven years on the heavy land I occupy here, 



which is of better quality than the Cambridgeshire farm ; but 



\/ both on a strong clay subsoil, and requiring under-draining. 



In both cases I have burnt all the borders, headlands, and 

 grass-balks in the fields, which had been enclosed with straight 

 quick fences about thirty years ago, but had yet been cultivated 

 as in the open field system, with high-backed lands, ploughed in 

 a serpentine direction, leaving in every field a great deal of waste 

 land as above described. This has not only furnished excellent 

 materials for burning, but also a supply of turf for draining, which, 

 cut in the wedge form, is one of the cheapest and best modes of 

 performing that necessary operation, without which the profitable 

 occupation of heavy land cannot be carried on. 



The work of burning is begun in May, and continued through 

 the summer, in heaps, containing from 50 yards to 100 yards 

 each, at an expense of 6c?. or 7d. a-yard, which includes every- 

 thing except a few roots and brush-fagots, the quantity of which 

 varies according to the supply of turf. The average value of the 

 wood consumed is about lO^*. for every hundred yards of ashes. 

 The great art is to let the clay burn slowly, which depends very 

 much upon the proper formation of the walls, which are of turf, 

 as the ashes then turn out black for the most part, and are con- 

 sidered much better than when they are red and clinking like 

 bricks. The more turf and vegetable matter the better (as weeds. 



