SCIENCE WITH PEACTICE, 1845 TO 1873 109 



discoveries increased tlieir utility : swedes and mangel- 

 wurzels on the one side, spring vetches from the other, 

 fill the gap which intervened between moisture-loving, 

 frost-dreading turnips and later green crops. Geology and 

 chemistry gave their invaluable aid to tillers of the land. 

 Geology taught the reasons which govern the superfluity 

 or the absence of bottom water, furnished definite classifi- 

 cations of soils, ascertained the composition of their 

 different strata, explained the principles that control their 

 capabilities and degi'ees of fertility. Chemistry reveals 

 by its analyses the elements on which agricultural values 

 of land depend, suggests how to remove differences or 

 supply deficiencies, equalises the characters of soils, re- 

 stores the properties which different plants exhaust, and, 

 in a word, assists every branch of husbandry, from the 

 manuring of the land to the production of milk, from the 

 growth of corn to the fattening of cattle. The triumph of 

 chemistry is summed up in the system of successive 

 cropping without impoverishment which has been esta- 

 blished by the experiments of Sir John Lawes and Dr. 

 Gilbert. Mechanical inventions completed what geology 

 and chemistry had commenced. The soil is not only im- 

 proved by drainage and artificial manures, but by subsoil 

 and trench ploughs and deeper cultivation ; it is more 

 easily tilled by the lighter and better implements which 

 replaced the cumbrous plough with its shoe-like share 

 fitted on to the wooden chip, and which, working at the 

 lightest possible draught, show clean-cut, level-edged, un- 

 broken rectangular fun'ows. Instead of the hawthorn tree 

 which Markham recommended for a harrow, new imple- 

 ments are adapted for light or heavy lands, as well as clod- 

 crushers, and horsehoes and scarifiers to cleanse the foul- 

 ness of the land. Thus the soil is better prepared for the 



