PLASTER FOR TREES. 



PLOUGH. 



venally in the possession of the farmer, in 

 fact, equal to them for immediate effect upon 

 those grasses. Now, coal-ashes usually con- 

 tain about 10 per cent, of sulphate of lime; 

 and, therefore, a dressing with 50 bushels of 

 coal-ashes per acre is equal to an application 

 of about 5 bushels of gypsum ; the remaining 

 portion of the ashes consists principally of 

 about 10 per cent, of lime and sand, and a 

 small portion of red oxide of iron and alumina: 

 so that the gypsum is here again evidently the 

 active ingredient the other constituent parts 

 being nearly inert substances. My own ex- 

 periments and observations have been con- 

 firmed by many others within the last two 

 years, for gypsum is evidently creeping gra- 

 dually into use as a manure for the grasses. 



In England, the expense of the application 

 of the gypsum is about 7*. per acre ; this sub- 

 stance being usually sold in London for about 

 2f. 10s. per ton at Reading and Southampton 

 at Is. 3d. per bushel. In the midland counties 

 it may be had at a still more reasonable rate ; 

 thus, in Derbyshire, it is so plentiful that the 

 farmers' cheese-room floors are commonly 

 formt 1 '! with it; it abounds, too, in the north 

 of England. The comparative produce of the 

 gypsumed over not-gypsumed land is very 

 great; it of course varies in amount. I have 

 seen it double the produce of clover hay, and 

 give an equally copious crop of lucern ; but 

 this \-.i<{ I invariably cut green for soiling. 



Mr. Smith, of Highstead, found still greater 

 benefit from the use of gypsum to his clover 

 leys; for where the simple soil produced 1 ton 

 only i"-r acre of hay, the portion of the same 

 soil to which 5 bushels per acre of gypsum 

 had been applied yielded 3 tons ; the first yield- 

 ing only 20 Ibs. of seed, while the latter pro- 

 duced 105 Ibs. Mr. Smith, too, first noticed 

 what my own observations have confirmed 

 that cattle, horses, &c., always prefer the grass 

 growing on the gypsumed portion of the field 

 to any other. The same remark is made by 

 those who spread coal-ashes on their grass 

 leys: the peat-ashes of Berkshire produce the 

 same effect. 



The general introduction, then, of gypsum, 

 as a top-dressing for the artificial grasses which 

 I have mentioned, is certainly an object of no 

 mean interest to the farmer, especially if he cul- 

 tivates the poor inland soils of England, where 

 artificial manures are scarce, and the carriage 

 of even the most portable is expensive ; for 

 gypsum possesses, in this respect, two advan- 

 tages combined, which do not belong to any 

 other, even of the saline manures : its first cost 

 is trilling, and its carriage light, since a wagon 

 will convey sufficient gypsum to dress 30 acres 

 of grass. 



PLASTER FOR TREES. See CAXKER. 



PLASTIC CLAY. Clay used in the manu- 

 facture of pottery. 



PLATYPHYLLUM CONCAVUM, or 

 KATY-DID. A kind of grasshopper found in 

 the United States. Dr. Harris, who was the 

 first to give a scientific description, has called 

 it Platyphyllum concavum. The front of its head 

 is obtuse, body of a pale-green colour, the 

 wing-covers and wings beipg somewhat darker. 

 Its thorax is rough like shagreen. The musi- 



cal organs of the male consist of a pair of 

 taborets, formed by a thin, transparent mem- 

 brane, stretched in a strong half-oval frame in 

 the triangular overlapping portion of each 

 wing-cover. During the daytime these insects 

 are silent, and conceal themselves among the 

 leaves of trees; but at night, they quit their 

 lurking-places, and the joyous males begin the 

 tell-tale call with which they enliven their silent 

 mates. This proceeds from the friction of the 

 taboret frames against each other when the 

 wing-covers are opened and shut, and consists 

 of two or three distinct notes, almost exactly 

 resembling articulated sounds, and correspond- 

 ing with the number of times that the wing- 

 covers are opened and shut; and the notes are 

 repeated, at intervals of a few minutes, for 

 hours together. The mechanism of the tabo- 

 rets, and the concavity of the wing^covers, re- 

 verberate and increase the sound to such a de- 

 gree, that it may be heard, in the stillness of 

 the night, at the distance of a quarter of a 

 mile. At the approach of twilight the katy- 

 did mounts to the upper branches of the tree 

 in which he lives, and, as soon as the shades 

 of evening prevail, begins his noisy babble, 

 while rival notes issue from the neighbouring 

 trees, and the groves resound with the call o 

 "katy did, she did," the live-long night. From 

 the head to the end of the wing-covers, this 

 insect measures rather more than 1 inch, the 

 body alone being I inch in length. The piercer 

 is broad, laterally compressed, and curved like 

 acimeter; and there are, in both sexes, two 

 little thorn-like projections from the middle of 

 the breast between the fore-legs. It is found 

 in the perfect state during the mouths of Sep- 

 tember and October. (Hurrix.) 



PLEASURE-GROUND. That portion of 

 ground adjoining a dwelling-house in the 

 country; and which is exclusively devoted to 

 ornamental and recreative purposes. In the 

 ancient style of gardening, the pleasure-ground 

 was laid out in straight walks, and regular or 

 symmetrical forms, commonly borrowed from 

 architecture ; but in the modern style, it is laid 

 out in winding walks, and in forms borrowed 

 direct from nature. A portion of lawn or 

 smooth grassy surface may be considered as 

 essential to the pleasure-ground under both 

 styles. See GARDENING, LAWIC, and PARTERRE. 



PLOUGH. (Sax. Plou ; Dan. Ploegh.) A 

 well-known, perhaps the most ancient, cer- 

 tainly the most valuable of all agricultural im- 

 plements. There are traces of it in even the 

 earliest of all written authorities, and, judging 

 of its importance in agriculture, we can hardly 

 imagine it possible to carry on extensive sys- 

 tems of cultivation in any period or country 

 without its assistance. By consulting the sa- 

 cred records, we find, that in very early times 

 they ploughed with two oxen (Deut. xxii. 10), 

 that their plough had a coulter and plough- 

 share (1 Sam. xiii. 20), and that the> were 

 early aware of the advantages of a win'er's 

 fallow (Prov. xx. 4). It is certain that .heir 

 ploughs were long since furnished with vi heels ; 

 a fact which is proved by the drawings 01 the 

 early Greek ploughs which have escaped to us 



Hesiod (Works and Days, p. 50 *41) advised 

 the Greek farmers to have a spare plough, thai 



899 



