OBSERVATIONS ON THEIR CONSTRUCTION AND USES. 79 



to the spade ; and with these two implements the settler in a new 

 country might cultivate ground already cleared so as to produce in 

 abundance every vegetable which was found suitable to the climate 

 and soil. 



But though a garden of the simplest kind may be cultivated with 

 no other implements than a spade and a knife, yet for a garden con- 

 taining the improvements and refinements common to those of modern 

 times, a considerable variety of implements is necessary or advanta- 

 geous. Some of these are chiefly adapted for operating on the soil, 

 and they may be designated as tools ; others are used chiefly in pruning 

 and training plants, and may be called instruments ; some are for 

 containing plants or other roots, or for conveying materials used in 

 cultivation, and are properly utensils ; while some are machines calcu- 

 lated to abridge the labour of effecting one or more of these different 

 purposes, or reduce the cost of keeping ground in good order, such as 

 the mowing machine. 



General Observations on the Construction and Uses of the Implements 

 used in Horticulture. 



Implements may be considered with reference to the mechanical 

 principles on which they act, the materials of which they are con- 

 structed, the saving of labour which they effect, their preservation 

 and their repairs. 



All tools and instruments, considered with reference to the mecha- 

 nical principles on which they act, may be reduced to the lever and 

 the wedge ; the latter serving as the penetrating, separating, or cutting, 

 and sometimes the carrying part ; and the former, as the medium 

 through which, by motion, force is communicated to the latter. All 

 the different kinds of spades, shovels, and forks have their wedges 

 in the same plane as the levers ; all the different kinds of picks, 

 hoes, and rakes have their wedges fixed at right angles to the 

 levers. The blades of knives and saws are no less wedges than 

 the blades of spades or rakes, only their actions are somewhat more 

 complex ; every tooth of the saw acting as a wedge, and the sharp 

 edge of a knife consisting of a series of teeth so small as not to 

 be visible to the naked eye, but in reality separating a branch by 

 being drawn across it, on exactly the same principle as the saw. 

 The series of combinations which constitute machines, when analysed, 

 may be reduced to levers, fulcrums, and inclined planes ; and 

 utensils depend partly on mechanical construction, and partly on 

 chemical cohesion. It is only by understanding the principles on 

 which an implement is constructed that that part can be discovered 

 where it is most vulnerable when used, or most liable to decay from 

 age. In all tools and instruments the vulnerable point is the fulcrum 

 of the lever, or the point where the handle is connected with the 

 blade or head. Another reason why failure generally takes place in 

 that part is, that the handle is there generally pierced with a nail or 

 rivet, which necessarily weakens the wood by breaking off or sepa- 



