Sheraton, Thomas; Bensley, Thomas; Mathews, James; Bensley, Thomas [Oth.]; Mathews, James [Oth.]; Terry, George [Oth.]; Jordan, Jeremiah Samuel [Oth.]; Wayland, L. [Oth.]: The Cabinet-Maker And Upholsterer's Drawing-Book: In Three Parts (London: Printed For The Author, By T. Bensley; And Sold By J. Mathews ... C. Terry ... J.S. Jordan ... L. Wayland ... And By The Author, 1793)

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Prob. XVII. Fig. 28.
To draw an Oval by means of a notched piece of wood
and a fquare.
I propofe this method as a good make-fhift, where a proper
tramel is not to be had, and when, perhaps, the method or
drawing ovals by the foregoing rules may have efcaped the
memory, and no book near at hand to affift it.
Operation.—Let f i be the long diameter, and take any
fquare, by means of which draw the line e t at right angles,
or fquare with it. Then notch out a piece of thin deal, as a g,
to fuit the thicknefs of the fquare, fo that the bottom of g
may reft on the furface of the oval, and not prevent a from
palling in the circumference f e. From the pencil point near a
to the end near g muft be equal to half the long diameter gf,
and from the notched part a to the pencil point a muft be
equal to half the fliort diameter e g. Laftly, place your fquare,
and with one hand keeping it unmoved on the two diameters,
by the other fweep the elliptic arch e f for one quarter. How
to proceed to the other quarters muft be evident to every one,
and therefore it is unneceftary to fay more.
The truth of this method will appear to every one by
I obferving,