Horse-hoeing husbandry : $b or, an essay on the principles of vegetation and tillage. Designed to introduce a new method of culture; whereby the produce of land will be increased, and the usual expence lessened. Together with accurate descriptions and cuts of the instruments employed in it.Tull, Jethro
Science
Horse-hoeing husbandry : $b or, an essay on the principles of vegetation and tillage. Designed to introduce a new method of culture; whereby the produce of land will be increased, and the usual expence lessened. Together with accurate descriptions and cuts of the instruments employed in it.
Tull, Jethro
Agriculture -- Early works to 1800; Plows; Tillage
But yet a quicker Way is, to set the Tongue, by the Setting-screw up
to the Edge of the Hole; and, when it is forced back, measure from
the Tongue to the nearest Part of the Hole, which will ever be a
perpendicular Line drawn from the Centre of the Hole to the Place of
Pressure above-mentioned, and make another Mark there: Now the Distance
between these Two Marks is the Measure (near enough) of the Tongue’s
Play at the Place of Pressure. Tho’ this Line drawn on the Side of the
Mortise be not exactly perpendicular to the Surface of the Tongue, but
only to its Edge; yet the Difference is next to nothing, and not to be
regarded.
If its Measure be a quarter of an Inch, it is what Experience shews to
be of a good Size for all Corn and Peas; a little less is no Harm, but
greater is the most fatal Error, into which most of the Pretenders to
the making of this Machine have fallen; they give the Tongue half an
Inch, sometimes Three quarters of an Inch Play. The Mischief of this
Error is yet farther increased, if the Spring be weak, if the Mortise
have too great a Bevel, or if the Angle made by the Tongue at the upper
Edge of the Mortise be too acute.
When the Tongue has too great Play, the Seed is apt to be turned out
too fast, or else too slow, in spite of the Driller. For when the
Tongue is set at its due Distance from the Spindle, and is thrust quite
back by the Seed pressed against it by the Turning of the Notches; but
the Spring being unable to return the Tongue to its former Place at
such a Distance, at the time of passing the Intervals which are betwixt
the Notches; then the Space between the Spindle and the Tongue being
too open, the Seed is sent down too fast.
To prevent that, they set up the Tongue to the Spindle; and then,
as often as the Spring happens to overcome the Force of the Seed’s
Pressure (as sometimes it will), it is sent out too slowly.
The Inequality of the Running of the Seed makes such Boxes useless,
which the Expence of Two-pence (for another Spring, or new Seasoning
of that) at most would rectify, if the Maker understood how to mend
his own Work. If time did permit, more should be said on this Point,
because I find it is the _Pons Asini_ of a Workman. Sometimes it may
be prevented, when the Spring is too hollow, and gives too much Play.
Screw the Screw, that holds it on the Tongue, down closer, so that the
lower Part of the Screw’s Head press against the Spring, and thereby
force its Middle nearer to the Tongue, until you find its Play lessened
to its just Distance.
The Spring, remaining in this compressed State, has lost the weakest,
and retains only the strongest, Part of its elastic Force. Therefore,
if you find it then too stiff, make it weaker by Filing or Grinding, or
else put another into its Place, which is honestly worth no more than
Two-pence.
This Holding-screw has a pretty broad Head, and is screwed in by a
Notch, like the Screw-pin of a Gun-lock.
Public-domain text, read in full here on John Shaqi.
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