THE SUBJECT CONTINUED. 209 



steam to a plough. There is no affinity between 

 them ; any more than, as I said before, between a 

 horse and a spade. 



I have found it inexpressibly difficult to get this 

 leading postulate clearly and once for all understood. 

 Till it is so it is hopeless to attempt to proceed. The 

 idea of an instrument to be dragged through the soil, 

 as a plough is, from one end of a field to another, 

 poisons, more or less, nearly every effort towards 

 steam-cultivation I have seen. How difficult it is to 

 wwlearn ! 



When the attempt was first made to run steam- 

 carnages on common roads, it was soon found that 

 however good a macadamized surface might be for a 

 wheel to roll upon, under a carriage drawn by horses, 

 it broke away into a perfect gravel-bed when the 

 new power, instead of pulling the carriage (the wheels 

 simply rolling underneath), laid hold of the Wheel 

 itself, and produced the locomotion of the vehicle by 

 forcibly driving that round. The very best road 

 gave way under the severe friction of this new mode 

 of producing locomotion, and so did the tires : and 

 nothing could be done till both road and wheel were 

 made of solid iron. The new power requires a new 



p 



