This armature plate revolved in front of a field plate carrying two pieces of tin-foil backed up by larger pieces of varnished paper.
A yard scale of varnished paper, made out locally for quadrant elevation with regard to height of site, was usually pasted over this.
The axis P N is made of varnished glass, and so are the axes that join the three plates with the brass axis N 0.
The articles are first fashioned by joining the soft material; they are then varnished, and afterwards cured in ovens heated to about 135° C. The fine vulcanized " spread sheets " are made by spreading layers of indiarubber solution, already charged with the requisite proportion of sulphur, on a textile base previously prepared with a mixture of paste, glue and treacle.
Sempervirens, varying from brownish red to very deep brown; oiled and varnished, it has been used in cabinet work.