1691. The usual mechanical agents employed in garden-culture may be classed as follows: ï¿½ 1. Tools, or simple implements for performing operations on the soil, and other dead or mineral matters; 2. Instruments for performing operations on plants, or on insects and vermin; 3. Utensils for habitations of plants, or the deportation or retention of either dead or living materials; 4. Machines, or compound implements, for any of the above or other purposed; and, 5. Articles adapted, manufactured, or prepared, so as to serve various useful purposes.