Ch. III.] 



SPIKY ROLLERS. 



37 



provenient has been made by constructing them of double cylinders, placed 

 so close together as to admit of the spikes intersecting each other, so that 

 they clear the dirt as the roller turns. When thus made, they are very power- 

 ful, for their weight is such as to break the hardest clump of dry clay, 

 and the intersection of the spikes between each other grinds it almost to 

 powder. When made in the common form, of a single wooden cylinder, 

 the spikes are about three inches in length, and nearly the thickness of the 

 thumb at the base, though somewhat pointed at the other extremity, and 

 driven into the wood in the quincunx order. It is in this form a most effi- 

 cient implement; but if made double, then it is almost unnecessary to say 

 that the spikes must be placed in regular rows, each about nine inches 

 apart. A very complete one, which is described in the Leicester Report as 

 being in use on Lord Moira's land, consists of two rollers, each about nine 

 inches diameter, armed with eight rows of spikes fixed in a frame, and 

 mounted upon wheels about 3^ feet high, with double shafts fixed on the 

 frame. There is also an upright post windlass and power of puUies fixed 

 upon the frame to raise or lower the roller at pleasure. This part of the 

 machine we, however, consider unnecessary ; for the object of raising the 

 machine for the purpose of carriage upon the roads might be attained by 

 the more simple plan of wheels upon moveable cranks ; we therefore merely 

 insert a representation of the mode of arranging the spikes, without noticing 

 the frame. 



The spikes, thus working in and in, mutually cleanse each other, and if 

 made with spiked cast-iron wheels, hooped round the cylinder, they could 

 be more correctly formed than when the sjiikes are driven into the timber. 

 W^hen applied to fallows, it is very efficient on land which is so stiff as to 

 bear the clods of the common one ; and although we agree with Marshall, 

 "that one effectual crush by a plain roller is worth a dozen ])artial inden- 

 tures by a spiky one*," yet when the ground is too hard to subnnt to its 

 pressure, the spikes will then be found to add greatly to its power. 



In some cases, rollers are made to act in nearly the same manner as those 

 with spikes, by having solid wedge-like rings of cast iron, with a hole through 

 them to receive a stout wooden axis. These wheels are each 2^ inches 

 thick, and are made moveable, so that they can be placed at different dis- 

 tances. They are sometimes 3 feet in diameter, and have been loaded so 

 * Minutes of Agric. Digest, p. 79. 



