668 Dr. ingenhousz’s Improvements 
of wood. In the middle of the two pillars was a hole, 
about an inch and an half diameter, fitted to receive a 
wooden axis, which could be placed in, and taken out, at 
pleafure. Upon this axis were to be ftuck the pafte-board 
disks; and a flat board, three inches broad, covered on 
both fides with flannel, and over this with a hare’s skin, 
was to be placed between each paile-board. The two 
fquare pillars were alfo to be wrapped up firll with flan- 
nel, and over that with hares skin. 
The flat boards, to be placed between the pafte-board 
disks, had each a notch in the center, to give room for 
the axis to turn round freely. Thefe flat boards could be 
brought as near one another as was required by two 
wooden male fcrews, placed at the upper and lower end 
of the frame, which reached from one fquare pillar to the 
other; which fcrews were to receive a notch cut out at 
the upper and under end of each flat board, in order to 
keep them fteady in their vertical fituation. A female 
fcrew, turning upon thefe horizontal male fcrews, was 
placed between each of the flat boards at their upper and 
under extremities, and ferved to bring each of the disks 
as near in contact with the hares skins as was required to 
receive a proper friction. 
The three pafte-boards were fixed in the frame, and 
whirled round. The electricity excited was fo ftrong 
that 
