1847. THE CUL TIVAT0R - 15 
SCIENCE OF MECHANICS, APPLIED TO AGRICULTURAL PURPOSES, 
In the construction of the more perfect and complex 
machines used in the arts, the principles of mechanics 
are closely studied in givnig a due proportion of light¬ 
ness and strength to every part. But in the more simple 
and common implements for the farmer, mere guess work 
too often becomes the only guide. It appears to some 
altogether trifling, to attempt to apply with precision 
scientific principles to the shaping of a hoe-handle or 
a plow-beam. Yet a little reflection will show that 
it is a matter not to be summarily rejected. 
The simplest tool, which is constantly used, should 
be formed with a view to the best application of strength 
to effect the intended purpose. The laborer, who 
makes two thousand strokes with the hand-hoe in an 
hour, or twenty thousand in a day, should not wield a 
needless ounce of weight in the implement. If any part 
be made unnecessarily heavy, even to the amount of 
half an ounce only, the force repeatedly expended to 
keep this in constant motion, amounts in the aggregate 
to no less than twelve hundred and fifty pounds a day, 
or requires a force equal to the moving of that amount, 
which ought to be exerted against soil and weeds. 
Again, a farm-wagon usually weighs nearly half a ton ; 
many of them might well be reduced 50 lbs. in weight, by 
reducing the size or altering the shape of parts where 
strength is not needed, without at all lessening the 
strength of the vehicle. Calculation will show, then, 
that the amount gained every year, by this reduction, to 
every farmer who drives his wagon on an average only 
five miles a day, will be equal to the conveyance of 
thirty bushels of wheat to a distance of forty miles. 
Similar estimates might be made in many other cases ; 
and if all the improvements were thus made which might 
be, the whole gain would be by no means trifling. 
We shall endeavor to illustrate this subject by a few 
examples. In the construction of the simplest tools, as j 
the handles of hoes and axes, rakes, and pitch-forks, a 
form convenient for grasping by the hand, as well as for 
strength is needed. The common axe-handle is usually 
well formed for both these purposes—the flat shape, 
for strength, edgewise, and with the greatest width at 
the entrance of the socket, where most strength is re¬ 
quired. Fork handles are often well made, but not 
unfrequently are quite defective in a combination of 
strength and lightness. The greatest strength being 
needed at the middle, where fracture usually takes 
place, they should here be of larger size, at the same 
time that full size must be allowed for a perfect fitting of 
the prongs to the handle. In fig. 2, a shows a well- 
formed handle, and b, one badly formed. Hoe-handles, 
not needing much strength, lightness and convenience 
for the grasp of the hand, should be mainly sought . For 
the latter purpose, there should be an enlargement at 
the upper end, to prevent the hand slipping 5 the rest 
should be nearly of equal size throughout. For light¬ 
ness, the weight should be lessened as much as possi¬ 
ble towards the blade, nearly all the motion being in 
this direction, the upper end being in a manner the cen¬ 
tre of motion ; hence it is highly important that the 
lower part be made as slender as possible, that the con¬ 
stant movement be not impeded by a needless ounce. 
The chief reason that the old hoes, with a large ring 
or socket attached to the blade, were so much less ef¬ 
fective than the best modern hoes, was the large and 
heavy form of the lower part of the handle. Fig. 3, 
represents two hoes, a being a well-formed handle, and 
b a clumsy one. Rake handles are usually made so as 
to break in the middle ; hence, the size should be there 
increased, and diminished at the ends. The same re¬ 
mark applies to the heads of rakes. Horse-rakes should 
be made as light as possible ; the head or main bar is 
usually of the same size throughout, but it may be much 
diminished in weight by an observance of the principles 
of mechanics. Plow-beams are often unnecessarily 
cumbersome, the greatest strength being needed at the 
junction of the mould-board, the least near the forward 
end, or farthest from the centre of motion. It very 
rarely happens that the beam ever breaks just back of 
the clevis, hence this part may be often much lightened. 
The limits and character of this article will not ad¬ 
mit of a full or accurate examination of the mathemati¬ 
cal principles, applying to the construction of imple¬ 
ments and machines ; but a few of the principles of 
almost constant application may be superficially ex¬ 
plained by figures. If a bar of wood, a , fig. 4, is set, 
fixed in a wall, to support a weight at its extremity, it 
will possess as much strength for this purpose when it 
has the form exhibited in the figure, as if of an equal 
size throughout; that is, a considerable portion of a bar 
of equal size may be cut away without lessening its 
strength.* The same reasoning obviously applies to a 
bar supported at the middle, with a weight at each end. 
It also follows as a matter of course, that the same 
shape is to be given to each part as to the single one in 
fig. 4; and would therefore be of the form represented 
in fig. 5. The shape is not altered when it is support¬ 
ed at the ends, with the weight at the middle. Hence 
this form, or one similar, becomes the proper one for 
many purposes in practice, as for instance, the rounds 
and bars or poles of ladders, the bars of whippletrees. 
fork handles, See.; and the half length as in fig. 4, for 
* If accuracy is required, the following rule is to be observed. 
The bar is to be diminished, in passing outwards from the wall, 
so that the breadth multiplied by the square of the depth shall 
always bear the same proportion to the diminished distance from 
the outer end That is. if b c be the depth at any place, then b d 
must be as the square of b c. This is on the supposition that the 
two vertical sides are parallel; if, however, the stick tapers on 
all sides alike, then b d must be as the cube of b c. In the former 
case, the lower edge of the bar will have a cubic parabola as the 
curve of its taper, the upper side being straight; and in the latter, 
the curve would be a common parabola. If the weights press on 
all parts of the bar alike, the form will be somewhat different. 
