DOI Seite / Zitierlink:
https://doi.org/10.11588/diglit.62828#0115
C 63 >
the two bradauls, and bring the ends of the line exactly to A,
at which point fix your pencil or piece of thin chalk, and begin
to defcribe in the manner that the hand exhibits, and the pen-
' cil, &c. will pafs through the points DBA as required.
I have found the preceding method vafily convenient in
marking out the circular ends of a fet of dining-tables; in
which cafe there is always an opportunity of flicking in the
bradauls at one fide of the board, after a line has been ftruck
to make the edge of the board flraight. Then, after drawing
a perpendicular line by a fquare and pencil from half the length
of your dining-table top, proceed as above, and you may draw
the femi-ellipfis juft to fuit the breadth of the board, if it is fo
required.
Prob. XVI. Fig. 27.
To defcribe an Oval by Ordinate Lines.
Where an Oval is wanted to be defcribed on a fmooth fur-
face that will not admit of any incifion or rough mark, the fol-
lowing method may be recommended.
Operation.—Draw the infcribed circle in Fig. 27 on a fepa-
rate board or paper, that the compafs foot may not mark the
fmooth furface. Divide one femi-diametcr of this circle into
8 any
the two bradauls, and bring the ends of the line exactly to A,
at which point fix your pencil or piece of thin chalk, and begin
to defcribe in the manner that the hand exhibits, and the pen-
' cil, &c. will pafs through the points DBA as required.
I have found the preceding method vafily convenient in
marking out the circular ends of a fet of dining-tables; in
which cafe there is always an opportunity of flicking in the
bradauls at one fide of the board, after a line has been ftruck
to make the edge of the board flraight. Then, after drawing
a perpendicular line by a fquare and pencil from half the length
of your dining-table top, proceed as above, and you may draw
the femi-ellipfis juft to fuit the breadth of the board, if it is fo
required.
Prob. XVI. Fig. 27.
To defcribe an Oval by Ordinate Lines.
Where an Oval is wanted to be defcribed on a fmooth fur-
face that will not admit of any incifion or rough mark, the fol-
lowing method may be recommended.
Operation.—Draw the infcribed circle in Fig. 27 on a fepa-
rate board or paper, that the compafs foot may not mark the
fmooth furface. Divide one femi-diametcr of this circle into
8 any