Agriculture Reference
In-Depth Information
seventeenth-century terms and their meanings in modern terminology to relate
more clearly to his instructions:
Hanse - The curved rise situated mid-way between the 'crown' and the springing-
line'; today known as the 'haunch'.
Scheam - The arc of a larger radius in the middle of a three-centred or elliptical
arch. It can also mean an arch that is the same as a segmental, but the voussoirs
radiate to the centre of the opening rather than the geometric radial-point of
the arc.
Sommering - The radiating lines representing the sides of the voussoirs as drawn to
either the 'striking-point' or from the 'extrados' to the 'intrados' of the arch face.
Chaptrels - An 'impost' or small capital more usually associated with vaulting.
Oxi (Oxigonium) - Or 'from the Oxi'. The setting out of the 'skewback' in a
straight (flat) arch by drawing an inverted equilateral triangle, with its apex at the
'striking-point', to create an angle of 60º.
Prick - The setting out mark made by the point of the compass or divider, when
'pricking-out' or marking the positions of the voussoirs along the extrados, and
sometimes the intrados, prior to drawing them out.
The difficulty today in correctly following and understanding Moxon's instruc-
tions so that either arch could be prepared and set as gauged work, becomes
very apparent upon reading his instructions on establishing the size of tight, or
very narrow, joints between voussoir templets:
…then make another fommering mould to fit between two of thefe Lines, abat-
ing fo much as you intend the thicknefs of your Joints of Morter to be, which
if you fet very clofe Morters, the breadth of the Line [black-lead pencil] will be
enough to allow… (Moxon, 1703, 275)
It is important to study and tease-out the hidden meanings within Moxon's
detailed explanations, made difficult by the use of old craft terms. It is how-
ever vital as one gains a deeper understanding of contemporary practices of
late seventeenth- and early eighteenth-century bricklayers, and the consequent
subtle aesthetic effects of their skills on their gauged arches.
The Semi-Elliptical Arch
The radiating, or sommering, of the voussoirs to the arc of the arch from Plate
8 of Moxon's treatise is taken from the centre, or 'striking-point', marked I (see
figure 83). Moxon gives two methods for setting out the haunch. In the first, the
extrados (F-L) and intrados (B-K) are divided into so many equal parts (in this
case 18 courses) and the lines then scribed between them. Moxon points out,
